JJJJ iiii wwww aaaa nnnn CCE - Jiwan Books Book-6 Final.pdfCarnivores have long sharp teeth for...

RNE AT TN II OS NK AO LO (B P

)N LA TW DI .J

l I lN AID

BOOKSJiwan

JiwanJiwanJiwanJiwanJiwanJiwan

© With the Publisher Price : ` 100.00

4809-11, 24, Ansari Road, Darya Ganj, New Delhi-110 002C-170, Naraina Industrial Area, Phase-1, New Delhi- 110 028

Published By :

CCECCESCIENCE

Question Bank

6

(Based On NCERT Syllabus)

PREPARED BY

Rekha Lalla

TEACHER RESOURCE

MANUAL

Chapter-1 : Food: Where Does It Come From?

Objective Type Questions

A. Fill in the blanks.

1. Protein and calcium 2. dairy 3. vitamins 4. apiculture

5. Crabs and lobsters 6. scavenger 7. Vitamins 8. stem

9. primary 10. Flat and sharp 11. Food

12. Decomposers and scavengers 13. Sun 14. Rice and fish

15. Idli and dosa

NCERT Questions

16. carnivore 17. herbivore 18. plant 19. milk

20. sugarcane

B. Write whether the following statements are true or false.

1. True 2. False 3. True 4. False 5. False 6. True

7. True 8. True 9. True 10. True 11. False

C. Match the two columns to make correct pairs.

1. a. iv b. iii c. i d. ii

2. a. iii b. i c. ii d. v e. iv

D. Multiple choice questions. Tick the correct option in each case.

1. d 2. b 3. a 4. b 5. d 6. c 7. c 8. b 9. b

10. b 11. c

NCERT Questions

12. d 13. b 14. b 15. c 16. b 17. a 18. d 19. d

E. Name them.

1. Potato 2. Scavengers 3. Nutrients 4. Food

5. Pisciulture 6. Apiculture

Descriptive Questions

F. Very short answer questions.

1. Animals can be classified on the basis of their food habits as herbivores, carnivores and omnivores.

2. Animals who eat only plant products are called herbivores. e.g., cows, horses.

3. Vultures and eagles are carnivore birds.

4. Omnivores are organisms that feed on plant as well as animal products. For e.g., crow, dog, cat, etc.

5. The food chain shows the link between various organisms for food.

6. Green plants are the primary producers. They are the only living beings that utilise the inorganic

constituents of the environment and convert them into organic compounds. All the other organisms

depend on plants directly or indirectly. So they are known as the primary producers.

7. Scavenging is both a carnivorous and a herbivorous feeding behaviour in which the scavenger feeds on

dead animal and plant material present in its habitat.

8. Cooked food is easy to digest.

9. Food gives us energy. Energy allows us to sustain every single function that is required for survival.

10. The main constituent ingredients are rice and urad pulse.

11. We eat different parts of plants which has starch or sugar stored in it like leaves, fruit, roots, stem and

even flowers.

12. Apple – Fruit

Potato – Stem

Carrot – Root®Jiwan Science CCE Question Bank Answer Key-6/1

®Jiwan Science CCE Question Bank Answer Key-6/2

NCERT Questions

13. a. NECTAR b. CARNIVORES c. HERBIVORES d. OMNIVORES

14. Bees store honey in comb cells which are capped over with wax.

15. Salt-From Sea, Soda-water and gas(Carbon-dioxide)

16. a. CHILLI b. FRUIT c. SOYABEAN d. SUGAR e. GROUNDNUT

G.Short answer questions.

1. Scavengers are organisms which feed on dead remains of animals and plants. e. g. vultures, hyenas,

crows.

2. A substance that provides nourishment essential for the maintenance of life and for growth.

3. Potato, sugarcane and banana have edible stems.

4. Herbivores : Animals which feed only on plant and plant products. e.g., cow, goat.

Carnivores : Animals which are flesh eaters. e.g. lion, tiger, vulture.

Omnivores : Animals which eat both plant and animal products. e.g. dog, cat, cow.

5. Herbivores have sharp, flat teeth in front for biting and flat grinding teeth at the back for cutting food.

Carnivores have long sharp teeth for tearing the flesh and carnivore birds have strong pointed beak.

6. Animals form a major source of food. They provide food in the form of meat, chicken, egg, milk, honey,

etc. The most important and nutritious animal product is milk, obtained from animals like cows, buffaloes,

camels and goats. It is consumed by both vegetarian and non-vegetarians. Meat is obtained from many

animals commonly, goat, chicken, fish and in some places pigs and cows. Seafood like crabs, prawns

and lobsters are also consumed by some. Eggs of hen and ducks are widely eaten for their protein and

iron. Honey is very rich in many nutrients and is a product of nectar of flowers, collected and processed

by honeybees.

7. A parasitism is the relation of two different kinds of organisms. One receives benefits by causing damage

to the other. Some examples would be a tick feeding on a dog, a mosquito feeding on a human or a leech

feeding on a human.

8. Scavengers are those organisms that feed on dead and decaying organic matter. They keep our

environment clean from dead organic matter. In this way, they prevent the accumulation of waste in the

environment and the spread of diseases caused due to such accumulation.

9. Mosquitoes do not have teeth as they do not eat solid foods. Instead of teeth mosquitoes have a

proboscis which is a long tube which they use for injecting saliva and for drawing blood from their victims.

10. 1. Noodles-Wheat flour 2. Pizza-cheese, wheat flour and vegetables.

H. Long answer questions.

1. Food provide us with energy and nutrients to grow, work, move and reproduce. We obtain all the

vitamins, minerals, proteins, fats and carbohydrates from the food we eat. They all are essential for

healthy functioning of our body.

2. Sprouts are germinating seeds. To prepare sprouts we wash the seeds like moong, chana or rajma and

soak them in water overnight. Then we drain the grain and tie them in a muslin cloth and keep it in a warm

place. After a day or two, we'll find tiny white sprouts coming out and it will grow longer with time.

3. a. HERBIVORES: A herbivore is an animal that gets its energy from eating plants, and only plants.

Omnivores can also eat parts of plants, but generally only the fruits and vegetables produced by fruit-

bearing plants. Many herbivores have special digestive systems that let them digest all kinds of

plants, including grasses. Examples : Moose, deer, cattle, sheep, rabbit and antelope.

OMNIVORES: An omnivore is a kind of animal that eats either other animals or plants. Some

omnivores will hunt and eat their food, like carnivores, eating herbivores and other omnivores. Some

others are scavengers and will eat dead matter. Many will eat eggs from other animals. Examples :

Bear, raccoon, chicken and human.

b. CARNIVORES : A carnivore is any organism that consumes animal tissues as the main component

of its diet (an important distinction from an omnivore). Example - polar bear.


DECOMPOSERS : Decomposers are organisms that process any decaying or already dead

organisms as an energy source. Example - worm.

c. DECOMPOSER : An organism, often a bacterium or fungus, that feeds on and breaks down dead

plant or animal matter, thus making organic nutrients available to the ecosystem. Examples:

moulds, worms, bacteria, fungus

SCAVENGER: An animal, such as a bird or insect, that feeds on dead or decaying matter.

Examples: vulture or hyena.

4. Food chain is the representation of interdependence of various animals for their food. All food chains

begin with a green plant and end with a carnivore. e.g., green plants are consumed by caterpillars which

are in turn eaten by birds. The birds are eaten by eagles. Therefore, the eagles depend on birds, birds

depend on caterpillars and caterpillars depend on green plants.

5. Honey is the thick, golden liquid produced by industrious bees, using the nectar of flowering plants and is

saved inside the beehive for eating during times of scarcity.

I. Give reasons.

1. Scavengers feed on dead carcasses and help in removing them from our surrounding. So, they can be

called the cleaners of the environment.

2. Growth is due to multiplication of cells. It is possible only if the necessary nutrients are provided. Food

helps us to obtain these nutrients. So, food is essential for growth.

3. Green plants manufacture their own food with the help of materials available in the environment. So, they

are called the producers.

4. Carnivores depend on the flesh of other animals. So, they need teeth which can tear into the flesh. So,

their teeth are long and sharp.

5. In a food chain, if one specie goes extinct, the organisms dependent on them will go without food and

they will also perish. The organisms on which the extinct species was dependent will grow, multiply in

excess causing havoc in the environment.

6. A food chain always starts with a green plant because plants are producers.

NCERT Questions

7. Germinating seed have building blocks of life called proteins. This will help the plant to grow. But at very

high temp the protein lose its structure due to denaturation. Thus the boiled seed cannot grow into plant

when it is boiled.

8. Living organisms need nutrients to live. They also need nutrients for energy, growth, repair, reproduction,

and metabolism. Nutrients are found in the foods that organisms eat.

J. HOTS questions.

1. In humans, the canines help in tearing flesh whereas the incisors and the molars will be used in eating

chapattis.

2. Raw vegetables have a lot of fibre made of cellulose. Human digestive system cannot digest cellulose.

So the roughage is excreted in the humans. Herbivorous have the enzymes necessary for digesting

cellulose and so they can use the cellulose as food.

3. Humans cannot synthesize the organic compounds they need to survive unlike plants that can

synthesize their own organic compounds. Consumers don't have the ability to make organic compounds

from inorganic compounds so they rely directly or indirectly on the ability of producers to do that.

4. Carnivores can obtain their nutrition by killing other animals and then consume them while parasites can

obtain their nutrition from the living host.

Chapter-2 : Components of Food



1. Obesity 2. nutrients 3. Sugar, starch 4. Lactose

5. fructose 6. Saturated 7. ghee, butter 8. Rice, wheat

9. Blood, muscles 10. Milk, dal 11. iodine 12. Carbohydrates, fats

13. Proteins 14. Simple 15. sucrose 16. Fats

17. Pulses, nuts 18. Sunlight 19. electrolytes

20. Repair of worn out tissue, growth 21. Vitamin C 22. Goitre

NCERT Questions

23. Rickets 24. Vitamin B 25. scurvy 26. Vitamin A

27. vitamin, proteins 28. Vitamin 29. Obesity

30. Water and dietary fibres 31. Vitamin C


1. True 2. False 3. True 4. False 5. True 6. True

7. True 8. False

NCERT Questions

9. False 10. True 11. True 12. False

C.Match the two columns to make correct pairs.

1. a. iv b. ii c. v d. i e. iii


1. a 2. c 3. b 4. d 5. c 6. d 7. d 8. a

NCERT Questions

9. d 10. d 11. b 12. c 13. c 14. a

E. Name them.

1. a. Fats-butter, cream b. starch-wheat, rice

c. dietary fibre-vegetables and whole grain d. Proteins-chicken, pulses

2. Carbohydrates 3. Proteins 4. Vitamin A 5. Calcium



1. We have to include vitamins and minerals in our diet for strong bones and teeth.

2. PEM – Protein Energy Malnutrition, PCM–Protein Calorie Malnutrition—meaning there is deficiency of

proteins, as well as carbohydrates in the diet.

3. Fat is stored under the skin, around the heart and kidneys.

4. Deficiency of Vitamin D causes rickets.

5. Vitamin K helps in clotting of blood.

6. Iodised salt is used to prevent goitre.

7. Obesity is the condition of excess body weight.

NCERT Questions

8. a. protein, b. mineral, c. vitamin, d. nutrients, e. fat.

9. Milk

G. Short answer questions.

1. Carbohydrates are excellent sources of energy. So, we need them to meet our energy requirements.

2. Proteins are essential for body building. So, they are required for growth, development, repair and

replacement of damaged parts and maintenance of body parts.



3. A diet that provides all the essential nutrients in the right quantity is called a balanced diet.

4. Iron in our body plays an important role in formation of red blood cells. They help in making haemoglobin

which helps to carry oxygen through blood.

5. Night blindness causes difficulty in seeing after sunset. The person suffering from night blindness cannot

see clearly in dim lights.

6. Kwashiorkor and marasmus are classified as PCM.

7. S.No. Carbohydrate rich food item Protein rich food item Fat rich food item

1. Sweet Potato Moong dal, Peas Mustard oil

2. Rice Fish, egg, beans butter

3. White bread Milk, Butter milk, cottage

cheese (Paneer) Maize

8. Many unhealthy foods taste awful and many healthy foods taste great. It's all a matter of preference. Our

body craves for fat, sugar and salt. So, we eat for one thing, they of course taste good, but our body also

knows that calories are present in these type of foods. As well as other things our body needs. Our body

does need fat, sugar and salt. Just in much smaller quantities than we normally consume. After a time on

a healthy diet you can train your body not to crave unhealthy food as much. It just takes some strong will

power not to give in and eat the unhealthy foods.

9. The potato should be washed in water before cutting and there is no need to peel the potatoes as the

nutrients present in them are washed in water itself.

10. a. carbohydrates, fats, proteins, vitamins and minerals b. water and roughage.

11. Minerals are important in our bodies in that they are necessary for three main reasons. They help us build

strong bones and teeth. They also perform and maintain all bodily processes. Lastly, they turn the food

we eat into energy.

12. Water is important in people's daily diet because it helps in the digestion and absorption of food. Water

also assists in the regulation of body temperature, removal of waste and toxins, as well as blood

circulation. It has also been established that water is an important part of weight loss.


1. Carbohydrates are energy foods. They provide the cheapest source of energy. Carbohydrates are

present in foods as either starch or sugar. Sugar is the simplest and most easily absorbable form of

carbohydrates and it gives instant energy. Starch is not soluble in water. It needs to be digested before it

can be used. Cereals like rice, wheat, corn, etc., milk, fruits potato, sweet potato are good sources of

carbohydrates.

2. Vitamins and minerals play a very important role in body functions like digestion, respiration, secretion of

enzymes and hormones, development of strong bones, teeth, skin, protection from diseases and

maintenance of eye sight. Though they are required only in small quantities, they are actually important

for good health. Deficiency diseases caused due to lack of vitamins are as follows:

Vitamin Deficiency

Vit A Night blindness

Vit C Scurvy

Vit D Rickets

Vit B Beri Beri

Vit K Inability to clot blood leading to hemorrahage

3. The term balanced diet refers to meals eaten by human beings over a period of time, containing all the

nutrients necessary for proper growth and development in the right quantity—neither excess nor

deficient. Such a diet contains a variety of food stuffs. Lack of any one nutrient will lead to a deficiency


condition which will lead to many other interrelated problems. So, it is very essential to take in a diet

which is balanced.

4. Dehydration is a state in which body loses excess of fluid due to vomiting, diarrhoea or blood loss. This is

dangerous since it leads to electrolyte imbalance and so should be treated promptly. Oral Rehydration

Solution (ORS) is available with a combination of salts that restores the balance of electrolytes inthe

body cells. So, it is advisable to start on ORS in case of severe vomiting or diarrhoea.

5. Roughage is the dietary fibre present in our foods like whole grains, fruits, vegetables, etc. These are not

digested in our body and they do not provide any nutrient. But they add to the bulk and help in bowel

movement.

6. Kwashiorkor is a condition seen in children with severe protein deficiency. The symptoms include

swollen stomach with water retention, thin legs, patchy skin and in severe cases, slowing down of mental

development. Marasmus is a condition in children with severe protein as well as carbohydrate

deficiency. The child is thin, bony, fatigued and has a poor appetite. In severe cases, physical growth is

retarded and muscles are poorly developed.

7. The government has set up Primary Health Centres to help detect and treat children who are suffering

from severe deficiency diseases. To attract children to school, the government has also started Mid-day

Meal Schemes where they provide meals with nutritive value to students. Awareness is also spread

through media. Integrated child development schemes are launched to help in these initiatives.

NCERT Questions

8. a. Night blindness b. Vitamin A

c. Spinach or any green vegetables, carrots, papaya, mango, pumpkin

9. a. Chapattis b. protein, D c. butter d. calcium, iron

e. papaya f. iron g. peas, proteins.

I. Give reasons.

1. Nursing mothers require more proteins since the milk that is fed to the baby should be high in protein and

the mother's body uses a lot of proteins to form milk. So, the protein intake of nursing mothers should be

increased.

2. Our body wastes are collected from different organs by blood in soluble form. The blood then carries

them to the excretory organs. So water is very essential to dissolve wastes and eliminate them as urine

or sweat.

3. Obesity refers to excess body weight, physical exercise helps to prevent build up of fats in the body. If

lifestyle is sedentary, that is, which lacks physical activity, then carbohydrates and fats we consume get

deposited as fat under the skin and lead to excess body weight.

4. Deficiency of Vitamin C may result in delay in wound healing. Vitamin C is very important for skin

formation and so we should take enough foods rich in vitamin C.

5. Sunlight helps our body to make vitamin D. Vitamin D is essential for bone health so we need sunlight for

good health.

6. The thyroid gland at the neck region gets swollen when there is deficiency in the hormone secreted by it.

NCERT Questions

7. The saree turned into blue black as the saree was starched to make it stiff. Starch always gives blue

black colour with iodine and socks do not have any starch in it.

J. HOTS Questions.

1. a. Fruits such as iron-rich apples and tomatoes are great to eat when treating anemia. You can either

eat apples or tomatoes or drink 100% pure apple and tomato juice to treat anemia. Also fruits that

effectively treat anemia are plums, bananas, lemons, grapes, raisins, oranges, figs, carrots and

raisins when eaten in large quantities. Vegetables such as spinach, lettuce, beet, broccoli,

fenugreek, celery and kale are iron-rich, energy-filled vegetables that treat anemia effectively. These

vegetables are not only rich in iron but also Vitamin B-12 and folic acid, energy-boosting nutrients

that the body needs to heal from anemia. Beetroot juice is an iron-rich vegetable juice that those

suffering from anemia can drink as a tonic against fatigue and lethargy.

b. Vegetables-green, leafy vegetables; beets; potatoes and fruits -orange and tomato can be taken as

they all contain thiamine.

c. Citrus fruits like oranges, grapefruit, limes and lemons. Berries such as blackcurrants, strawberries,

raspberries, blueberries and cranberries, Cantaloupe melon and watermelon. Kiwi fruit. Vegetables

such as spinach, green and red peppers, tomatoes, cauliflower, cabbage, broccoli, brussels sprouts

and potatoes can be taken as they all contain vitamin C.

2. Bread is made out of flour that comes from grain kernels — usually wheat. A grain kernel has three parts:

the bran, the endosperm, and the germ (so called because it's the part of the kernel that germinates into

a new plant).Whole grains contain all parts of the grain kernel. But refined grains, like the flour used to

make white bread, have had the fibre-dense bran and the nutrient-rich germ processed out, leaving only

the starchy endosperm. This means that refined grain is not as rich in essential fatty acids, vitamin E,

magnesium and zinc. Some flour and bread manufacturers "enrich" their bread by adding extra vitamins

back in. But it's still better to eat whole grains. The fibre and protein from the bran and germ provide a

more constant source of energy, which will keep you going long after the energy from refined grains is

gone. The fibre in the bran can also mean whole-grain breads help people feel full longer, preventing

overeating.

3. Vegetables are naturally rich in fiber so the vegetarian person will not have any problem but the person

eating processed food and non-vegetarian diet will have the problem of constipation as the diet is devoid

of fibres.

4. Labourers always have a bunch of work to do. Therefore, they need much energy they could only get

through rest and proper diet. The more vigorous the activities you engage in, the more amount of food

you need to eat. Whatever you do, whether you are a nurse, a house wife, or a laborer, a well balanced

diet is all you need to stay healthy and fit. Since labour requires so much energy, it will be best for

labourers to eat carbohydrate rich foods while maintaining a balanced diet.


Chapter-3 : Fibre to Fabric



1. black, alluvial 2. plenty 3. cotton ,jute 4. bark

5. fibres around seeds 6. fabric 7. chemicals 8. sheep, goat, yaks

NCERT Questions

9. wool and silk


1. False 2. False 3. True 4. True 5. False 6. False

7. False 8. True 9. True 10. False 11. True 12. True

NCERT Questions

13. False 14. False 15. True 16. True 17. True 18. True

19. False 20. True 21. False 22. False


NCERT Questions

1. a. ii b. i c. iii d. iv

2. a. v b. i c. vi d. ii e. iii f. iv


1. c 2. a 3. c 4. b 5. b 6. a 7. a 8. b

NCERT Questions

9. a 10. b 11. d 12. c 13. c 14. c 15. b 16. d

17. b 18. b 19. c

E. Name them.

1. Cotton 2. Jute 3. Flax 4. Wool

NCERT Questions

5. Rope and coir mat 6. Cotton bolls



1. Fibres are long strands of molecules obtained from plants or animals.

2. Cotton, jute, silk are natural fibres.

3. Silk is obtained from silkworm.

4. Cotton is a soft and absorbent natural fibre.

5. Hemp and coir are used in making ropes.

6. Wool in used is making shawls and jackets.

7. Ginning is the process of separating fibres from cotton seeds.

8. Clothes provide protection from extreme climatic conditions like heat and cold. They protect the human

body from many things that might cause injury.

9. Clothes are mostly made from fibres which are obtained from either plants or animals.

10. Fibres are obtained from plants like cotton, hemp, jute and flax;and animals like sheep, camel, silk worm,

etc.

11. Silk and wool are obtained from animals.

12. Coir is obtained from the outer covering of coconut.

NCERT Questions

13. Yarn, fibres



14. a. COTTON, b. SPINNING, c. WEAVING, d. FIBRES

15. How do we classify the fibres? Give examples of each.

16. Natural– wool, cotton, jute, silk synthetic– nylon, polyester

17. Knitting


1. We wear clothes to protect ourselves from heat, cold and external injury.

2. People used leaves and animal skin as clothes before the invention of clothes.

3. Fibres are long strands of chemical molecules. When many fibres are spun together, we get a yarn.

4. Sarees, dress materials and curtain materials are made of cotton.

5. Jute is used in making jute bags and sacks, floor coverings, door mats, etc.

6. Weaving is a method of interlacing of yarns to form fabrics.

7. Handlooms are machines used to weave a fabric which is operated manually.

8. Synthetic fibres are made from chemicals in factories.

NCERT Questions

9. Dhoti, saree, lungi, scarf, shawl, dupatta, gamcha, pagadi

10. Black, warm, bolls, ginning, spinning, dyed, spun


1. Fibres can be classified as natural and synthetic. Natural fibres are obtained from plants or animals. They

are plant products like cotton and linen and animal products like wool and silk. Synthetic fibres are

produced from chemical molecules obtained from petroleum products. They are laboratory made and

have properties different from natural fibres. Examples of synthetic fibres are nylon, polyester and

acrylic. Fibres are spun into yarns which are interwoven into fabrics.

2. The cotton fibre grows around the seed of the cotton boll when the cotton bolls open up on maturing, the

fibre slowly dries up. Fibres are then separated from the seeds and spun into cotton yarns. This process

is called ginning and the fibres are called lint. These fibres are spun into yarns by spinning on a loom.

3. Coarse jute mats are used to cover vast areas of barren land to prevent soil erosion. So, they can be

called soil savers.

4. Coconuts are usually dehusked and the fibre is left in water for a few months. The fibres are then sifted to

remove dirt and beaten with wooden mallets to get usable fibre. It is then spun and dyed and is ready for

weaving.

5. Animals like sheep, goat, camel, angora rabbit, yaks, llamas, are used as a source of wool.Wool is

removed from sheep using special clippers by shearing. Then the wool is packed in bales and

transported to mills. Here, it is cleaned and combed by machines. The fibres are then knitted to make

fabrics.

6. Sericulture is rearing of silkworms for production of silk. The silkworms are fed on mulberry leaves. They

feed voraciously and spin a thread around themselves to form a cocoon. The cocoons are collected and

sent to factories, where the cocoons are boiled in water to kill worms and loosen the fibre.The fibre

obtained is spun into yarns and thus the silk fibre is obtained.

7. Synthetic fibres are manufactured from chemical molecules, in factories. They are stronger than natural

fibres and are more durable. They have a lot of good properties like quick drying, durability, are

economical, strong and wrinkle free. But they don't absorb sweat and air does not pass through them.

So, they can be uncomfortable in hot humid weather. They also catch fire easily.

8. The fibres are first separated from the source. They are then cleaned, combed and dried. The clean fibre

is then converted to a yarn by the process of spinning. The yarns are made up of several strands of fibres.

Spinning is done on the spinning machine, the yarns are woven or knitted to create fabrics.


9. Jute mats and coir mats are used to cover barren land to prevent soil erosion. These mats are spread

along river banks and hill sides to cover the soil and thus are soil is saved from erosion.

NCERT Questions

10. Cotton is typically planted in spring, again by machines, which can plant 12 rows of cotton seeds at a

time. Under good conditions, the plants generally are visible above the ground within a week. The

seedlings mature for about a month and a half, and then begin to flower. Flowering is very brief, and in

just a few days after the flower appears, it is gone, and in its place remains the part of the plant that ripens

into a pod called a boll. Over two to three months, the boll matures and the cotton fibres in it grow to their

full length. Harvesting occurs once the boll has split open, revealing the cotton, and the fibres have had

time to dry in the sun. The leaves of the cotton plant must usually be removed chemically before the

harvest, but in some areas, freezing temperatures will cause the plant to lose its leaves naturally. This

removal of the leaves allows the cotton to be machine-harvested. Once the harvest is complete, the

cotton is made into bales to be stored until it is ready to be ginned. At the gin, the bales are all cleaned to

separate the cotton fibers from dirt, lint, and the small, sticky seeds that grow as part of the ball of cotton

fibres. The de-seeded and cleaned cotton is then once again pressed into bales .At this point, the cotton

is still raw, as it has not been spun into yarn or thread.

Cotton fibres actually lend themselves very well to being spun into yarn. Once the fibers are aligned in a

process called carding, they naturally interlock as they are twisted and flattened for spinning.

Specialized mechanical looms weave the yarn into cotton fabric in much the same way as was done by

hand in prior centuries. These looms work at high speeds to interlace the yarns into a woven fabric known

as “gray goods.” Cotton fabric in this state must still be bleached and otherwise pre-treated before it can

be made into household products and clothing.

11. The process of arranging two sets of yarns together to make a fabric is called weaving. The process of

making yarn from fibres is called spinning. In this process, fibres from a mass of cotton wool are drawn

out and twisted. This brings the fibres together to form a yarn. A simple device used for spinning is a hand

spindle, also called takli. Another hand operated device used for spinning is charkha.

12. The process of making yarn from fibre is called spinning. In this process, fibres from a mass of cotton

wool are drawn out and twisted. this brings the fibres together to form a yarn.

I. Give reasons.

1. Cotton is ideal for summer moths— Being soft and absorbent, cotton is very comfortable in the hot

summer months, we feel comfortable in summer cotton clothes during hot and sunny weather.

2. Acrylic has fast replaced wool— Acrylic has fast replaced wool . It is true because acrylic is esy to

maintain, stronger than the natural fibre, thus have long life. Acrylic often remains safe from pests and

insects as well.

J. HOTS questions.

1. Mumbai is hot and humid post monsoon, in the month of August. It will be advisable to carry blended

fabrics like polycot or pure cotton which are absorbent and easy to dry.

2. Animal activists are against the process of making silk since it involves killing hundreds and thousands of

silkworms. Killing so many of them to obtain silk which is a luxury item for us, is considered

unacceptable.

Chapter- 4 : Sorting Materials into Groups





1. a. v b. iv c. ii d. ii e. iii

2. a. iii b. i c. ii d. v e. iv

3. a. iii b. iv c. i d. ii


E. Name them.



1. poor 2. float 3. CO 4. electricity2

5. density 6. lustre 7. fixed, shape 8. milk, water

9. fixed, shape 10. immiscible

NCERT Questions

11. rough 12. heavy 13. smooth surface 14. lustre

1. False 2. False 3. True 4. False 5. False 6. False

7. False 8. True 9. False 10. False 11. True 12. True

1. d 2. d 3. b 4. d 5. a 6. a 7. c 8. d 9. a 10. c

NCERT Questions

11. b 12. c 13. c 14. c 15. c 16. b 17. d 18. c 19. b 20. d

21. a

1. Wood 2. Atom 3. Classification 4. Oxygen

5. Gases 6. Transparent 7. Chair, table, door, window, cupboard

13. Silver turns black (what is known as tarnishing) due to exposure to the atmosphere. When silver comes

into contact with air, a chemical reaction occurs creating a sulphate stain on the finger known as silver

sulphate. But gold is not affected by the atmosphere like silver.

14. Raveena's mixture is in solution form as honey is soluble in water.

15. Yes his brother will be able to spot her as the glass door is transparent.

16. Cotton ball will first float in water due to the trapped air in cotton ball but after sometime when the cotton

ball absorbs water it sink in water due to its high density than water.

1. Ropes and chairs.

2. Wood, steel.

3. Living things breathe through respiratory organs like nose, lungs or gills.

4. The sense organs such as eyes, nose, skin, ear and tongue help us to feel the world around us.

5. Matter can exist as solid, liquid and gas.

6. Oxygen and carbon dioxide can dissolve in water.

7. Liquids that dissolve in water or other liquids are called miscible.

8. Plastic sheet can be transparent (cellophane paper) or translucent.

9. Metals are generally good heat conductors.

10. Copper is the most commonly used metal in making electrical wires.

NCERT Questions

11. Steel spoon

12. a. baby b. boat c. sand d. sand



G. Short answer questions

4. Living organisms are made up of cells. They have the ability to grown and reproduce. Living organisms

can also move on their own. Humans, plants, and animals are some examples of living organisms.

Nonliving things are man-made and do not carry the common characteristics of life. Non-living things

have no methods of movement. Some examples of nonliving things include buildings, automobiles,

books, and electronic goods.

9. Matter is defined as anything that has mass and takes up space. An example of something that is matter

could be a pen or pencil. An example of something that is not matter would be gravity or energy.

10. The main difference between an element and a compound is that while an element is the simplest form of

a substance that cannot be broken into simpler substances, a compound is a pure substance made out

of two or more elements. Compounds have chemical structures that are completely different from the

structure of the elements that make them up. Compounds can also be separated into their constituent

elements through a number of chemical processes.

NCERT Questions

11. a. round shapes – globe, basket ball, orange

other shapes – water, sugar, apple, earthern pot

b. eatables – orange, water, apple, sugar

non-eatables – basket ball, globe, earthern pot

12. Things which will float on water- There are all kinds of things that float in water. Items like wood, cork,

plastic and beach balls can float in the water. You can even float steel, like a huge ship, in water. It is not

necessary that things which float in water will float in kerosene also. The things that have lesser density

will float. Kerosene has lesser density than water. So, it floats in water. The things that have lesser

density than water will float in water. But there may be some substances that have lesser density than

water, but more density than kerosene. These substances will float in water, but sink in kerosene.

13. Rubber band, leaf, eraser, cooked rice, pulses and fresh chapattis are soft materials as they can be

compressed. Things which are difficult to compress are called hard materials like-pencil, a piece of

wooden board.

14. Soluble pairs – water and glucose, water and honey, water and turmeric,

Soluble pair – ground nut oil and mustard oil

Pairs in which one remains in soluble-water, rice flour and glucose, mustard oil, turmeric and water

15.

1. Classification is sorting things around us according to certain common characteristics.

2. Metals are good conductors of heat. So, cooking utensils are made up of metals.

3. Fishes breathe through gills.

5. Liquids do not have a fixed shape. So, they take the shape of the vessel in which they are poured.

6. Metals are highly malleable and ductile. So, they can be given any shape and design in jewellery.

7. Materials which have density lower than water can float on water.

8. Atom

Name of the material

salt

Green grass

Broken glass

A small thermocole box

pen

Iron nail

Glass marbles

A piece of sugar

appearance

dusty

solid

solid

solid

solid

solid

solid

solid

Transparency

opaque

opaque

transparent

opaque

opaque

opaque

translucent

opaque

Transparency

Dissolves in water

floats

sinks

floats

sinks

sinks

sinks

dissolves

Soluble/insoluble

soluble

insoluble

insoluble

insoluble

insoluble

insoluble

insoluble

soluble

S.No.

1.

2.

3.

4.

5.

6.

7.

8.

16. a. Making Utensils,Electrical appliances b. Furnitures, cable cover

c. Gas stove, fuel in Aeroplane d. flavouring, Preservative


1. Classification is important because it helps scientists understand the world around them better.

Classification is meant to organise information and objects. It also helps us to remember where different

organisms fall under as well as distinguish their characteristics.

2. Copper and aluminium are good conductors of electricity and are ductile. So, they can be drawn into

wires.

3. Solid – When atoms of any substance is very tightly packed, having no intermolecular space then that

substance is called as solid substances.

• They are rigid in structure.

• Have definite structure and volume.

• Have high density. Ex - wood etc.

LIQUID – When there is some intermolecular spaces between the atoms.

• They are fluid in nature.

• Don 't have definite shape or volume.

• Occupy the shape of the container in which it is kept. Less density then solid and more density then

liquid. Ex- water

GAS – When there is a large intermolecular space between the molecules.

• They are also fluid in nature.

• Have neither definite shape nor volume.

• Have lesser density then water. Ex - All atmospheric gases.

4. Water is liquid at normal room temperature. When heated, the molecules of water gain energy, move

apart and reach the gaseous form. On cooling to freezing temperatures, its molecules move closer and

gain the solid form. So, it can exist in all three states.

5. Transparent materials are capable of passing light through them. Translucent materials can allow some

amount of light to pass through while opaque materials do not allow any light to pass through.

6. Our body is a very good conductor of electricity. So, if there is leakage of current in a gadget, the body will

pass it to the earth and in that process suffer an electric shock. To avoid it, rubber or wooden slippers

should be worn as rubber and wood are insulators that will not allow the flow of current.

7. Magnetic substances get attracted by a magnet. Eg., iron, nickel and cobalt. Non-magnetic substances

do not get attracted by a magnet. Eg., copper, stainless steel, wood.

8. Two liquids are said to be miscible if they completely mix and thus form a homogeneous mixture. For

example ethanol and water, benzene and carbon tetrachloride etc.

Immiscible liquids are those which do not mix completely. A mixture of two immiscible liquids is not

homogeneous but heterogeneous. For example benzene and water.

NCERT Questions

9. Take a beaker full of water. Add all the materials in it and observe. The heavier materials will settle down

at the bottom or sink and the light materials will float at the top of the beaker.

10. Transparent means to let light pass through while translucent lets some light go in but not all of it. Some

examples of translucent materials are smoked glass, sheer cloth and thin plastic. Opaque objects allow

no light at all to pass through them. Examples of these different objects are glass, plastics and rocks.


I. Give reasons.

1. Metals are lustrous. Luster in metals is visible when it is smooth and polished. Iron rods used in

construction are not smoothened or polished. So, they do not shine.

2. Cooking utensils get very hot because they are made of metals which are good heat conductors. Wood

or bakelite is good insulators. So, they help us in handling cooking utensils without burning our hands.

3. Electrical wires conduct electricity. Plastics are insulators. So, covering current carrying wires with

plastic helps us to prevent electric shocks.

J. HOTS questions.

1. Birds on high voltage wires do not have contact with the earth which will complete the path of current. So,

they do not get an electric shock. Moreover the high tension wires are insulated.

2. When we open aerated drinks, a huge amount of air bubbles rise out of them. It is because a lot of carbon

dioxide is dissolved under pressure. When we release the pressure, the gas escapes.

3. An aquarium needs fresh oxygen dissolved in water to enable fishes to breathe. Air filter will allow the

oxygen to dissolve and prevent accumulation of carbon dioxide.

4. Gelatin silver print paper was made as early as 1874 on a commercial basis, but it was poor quality

because the dry-plate emulsion was coated onto the paper only as an afterthought. Later baryta coating

became a commercial operation which is used for lustrous or glossy print surface.

5. When ice freezes, tiny spaces form in the crystalline structure, these spaces can hold small bubbles of

air. These air bubbles cause the ice to be less dense than water, and also add a buoyant force, thereby

enabling the ice to float.


Chapter-5 : Separation of Substances



1. Air, soil 2. pure 3. Threshing 4. sieving / winnowing

5. Threshing 6. pure, mixtures 7. sedimentation 8. Filtration, loading

9. Distillation 10. evaporation 11. saturated 12. size

13. sedimentation

NCERT Questions

14. hand picking 15. Wheat and rice 16. winnowing 17. sedimentation

18. solid, liquid 19. threshing 20. filtration 21. evaporation

22. decantation


1. True 2. False 3. True 4. True 5. False 6. True

7. True

NCERT Questions

8. True 9. True 10. True 11. True 12. True

13. False 14. False 15. False 16. False 17. False


1. a. iii b. iv c. v d. vi e. ii f. i

NCERT Questions

2. a. iii b. iv c. v d. ii e. i


1. b 2. a 3. c 4. d 5. a 6. b 7. c 8. b

NCERT Questions

9. d 10. c 11. b 12. d 13. d 14. d 15. b 16. d 17. c 18. d

E. Name them.

1. Evaporation 2. Winnowing 3. Magnet

4. Liebig's condenser 5. Loading



1. Sieving is a method of separation used when size of particles in a mixture are varied.

2. Winnowing

3. In winnowing, lighter particles fall off. So difference in weight of the particles is the property used.

4. No, they can be separated by filtration.

5. Addition of alum (loading) will speed up sedimentation.

6. Evaporation and distillation are used to separate soluble solids from a solution.

7. No, water dissolves all states of matter.

8. Liebig's condenser is used for cooling hot vapours.

9. A separating funnel is used in separation of miscible liquids.

10. Decantation

11. Filtrate is the clear liquid collected after filtration of an impure solution.

NCERT Questions

12. Saima would be able to win the game as with the increase in temperature the solubility also increases.


1. Mixtures are substances whose components can be easily separated by physical means. This is used in

separation of mixtures.®Jiwan Science CCE Question Bank Answer Key-6/15


2. When light and heavy components are present in a mixture, winnowing is used to separate light

components.

3. During rainfall, the suspended particles of the atmosphere get loaded by rainwater and they are brought

down. So the air is free from suspended particles and we can see more clearly.

4. To separate insoluble solids from liquids we can use sedimentation and loading or filtration.

5. Threshing is separation of freshly harvested grains from their stalks.

6. Ultraviolet light is used for killing germs in water.

7. A solution which contains maximum solute, soluble at a given temperature is called a saturated solution.

NCERT Questions

8. Winnowing is used to separate lighter material from heavier ones.

9. We need to separate the components of a mixture for the following reasons:

a. Remove the unwanted impurities.

b. Remove the substances that are harmful for our health.

c. Obtain pure substances.

d. Separate two different, but useful components.

Examples:

a. Grain is separated from stalks, while harvesting.

b. We filter tea leaves after preparing it.

c. Milk or curd is churned to separate the butter.

10. Winnowing is a method to separate heavier and lighter components of a mixture by wind or by blowing

air. This method is commonly used by farmers to separate lighter husk particles from heavier seeds of

grain.

11. Husk or bigger pieces of dirt particles can be removed from a sample of pulses by handpicking.

12. Sieving is the process to filter components of a mixture of different sizes. Sieving allows fine particles to

pass through the holes of the sieve, while the bigger impurities remain on the sieve.

Sieving is used in flour mills to separate broken particles of grains from flour. It is also used at

construction sites to separate lumps, smaller stones from the mixture of sand and cement.

13. We can separate the sand and water from their mixture :

a. Allow mixture to stand undisturbed for sometime in a container.

b. Sand settles at the bottom of the container. It is called sedimentation.

c. Gently pour the water in another container (called decantation).

d. We may also use filter paper to remove fine particles of sand (called filtration).

14. Through sieving we can separate sugar mixed with wheat flour.

15. We can obtain clean water from a sample of muddy water :

a. Allow muddy water to stand undisturbed in a container.

b. After sometime, mud settles at the bottom of the container. This process is called sedimentation.

c. Upper layer is clear water.

d. Pour the clear water gently in another container. This process is called decantation.

e. To remove finer impurities we can filter this water again with the help of filter paper. This process is

called filtration.


1. RO ( Reverse Osmosis ) filters use a combination of techniques to provide clean and safe drinking water.

The water is first filtered to remove undissolved impurities. Then it is passed through activated charcoal

to remove odour and colour. The water is then passed through an ultraviolet chamber to kill harmful

microorganisms.


2. In a mixture of gram, sand and pebbles, grass can be removed by winnowing. Being light, it will fly away.

The sand, pebbles mixture should be passed through a sieve of small pores so that sand can be

separated from pebbles.

3. Sedimentation is a process of allowing the heavier particles of a mixture to settle down. Decantation is

the method of separating the clear liquid that is above the sediment, without disturbing the sediment.

4.

5. A mixture is a material containing two or more elements or compounds in any proportion and the

components of which can be separated by simple mechanical means. A mixture may be homogeneous

or heterogeneous. The constituents of a mixture can be separated by physical methods like filtration,

evaporation, sublimation, magnetic effect, etc. In the preparation of a mixture, energy is usually neither

given out nor absorbed. When we mix sugar and sand together, there is no energy change, i.e., energy is

neither evolved nor absorbed. A mixture has no definite melting point, boiling point, etc.

6. Two miscible liquids can be separated by the process of distillation if their boiling points are different. In

this method, the solution is heated so that the liquid evaporates and then the vapours are cooled to get

the pure liquid.

7. In our homes the water can be filtered and then boiled to kill microbes.

(i) Water can also be purified by using water filters and using ultraviolet lamps to kill microbes.

(ii) Water is purified by using reverse osmosis system, even unwanted minerals present in water are

separated besides killing germs.

8. Soluble solids in a mixture can be separated by boiling and evaporation. For example, salt in water or

sugar in water are separated by boiling the solution till all the water evaporates, the salt or sugar will be

left behind.

9. a.

Homogeneous Mixtures

Homogeneous mixtures have uniform

composition.

It has no visible boundaries of separation

between its constituents.

Some examples of homogeneous mixtures

are: salt in water, sugar in water.

S.No.

1.

2.

3.

Heterogeneous Mixtures

Heterogeneous mixtures have non uniform

composition.

It has visible boundaries of separation

between its constituents.

Some examples of heterogeneous

mixtures are: water and sand, oil and water.

Distillation

Separatingfunnel

Kerosene oil

Water

Stopoock

Beaker

WaterSeparating Funnel

b.

c.

10. In a mixture of water, salt, sand and iron filings, the following methods should be followed for separating

the components:

(i) Magnet should be passed over the mixture to remove all the iron filings.

(ii) Then the mixture should be dissolved in water.

(iii) Pass the solution through filter paper to separate the sand. The salt solution can be collected in a

beaker.

(iv) Boil the salt solution in the beaker till all the water evaporates. Salt is left behind.

11. Water is considered an important solvent because it can dissolve many substances. It is due to this

property that our body is able is transport much of the nutrients through blood and excrete the waste

materials. Many chemical reactions also take place in the presence of water. The oxygen and carbon

dioxide dissolved in water helps aquatic animals and plants to survive. So water is a very important

solvent.

Original Mixture

Test Tube

Filter paper

Funnel Residue

TestTube

Filtrate

Filtration


12. The solubility of a substance is increased by raising the temperature of the solution. Increase in

temperature helps to dissolve more solute.

NCERT Questions

13. a. They can make solution by dissolving the salt in water.

b. Mohan would be able to prepare a saturated solution.

14. Sand settles down at the bottom. The water and oil can be decanted from the top of sand and removed in

another tumbler or beaker. The immiscible liquids (oil and water) can be separated by using a separating

funnel. Salt which dissolves in water can be removed by evaporation.

15.We take a magnet and move it through the mixture till the whole of iron fillings are attracted by the

magnet. Oil and water can be removed by using a separating funnel. Filter the mixture. The sand is left

on the filter paper, and the clear common salt solution collects as a filtrate. Now, we heat salt solution. In

a few minutes, water evaporates, leaving behind dry common salt.

I. Give reasons.

1. When it rains the rain drops load the dust particle and make them come down to the ground. So, the

atmosphere becomes clear after the rain.

2. Water is capable of dissolving a variety of different substances, which is why it is such a good solvent.

And, water is called the "universal solvent" because it dissolves more substances than any other liquid.

This is important to every living thing on earth. It means that wherever water goes, either through the

ground or through our bodies, it takes along valuable chemicals, minerals and nutriments.

It is water's chemical composition and physical attributes that make it such an excellent solvent. Water

molecules have a polar arrangement of the oxygen and hydrogen atoms—one side (hydrogen) has a

positive electrical charge and the other side (oxygen) had a negative charge. This allows the water

molecule to become attracted to many other different types of molecules. Water can become so heavily

attracted to a different molecule, like salt (NaCl), that it can disrupt the attractive forces that hold the

sodium and chloride in the salt molecule together and, thus, dissolve it.

3. The process of separating heavier insoluble solid particles mixed in liquid is called sedimentation. For

separating we left mixture undisturbed for some time. The heavier particles settle down at bottom is

called sediment. The method of collecting clear liquid from sediment is called decantation. The settled

impurities are to be removed to get a pure liquid so the Sedimentation and decantation are used

together.

J. HOTS questions.

1. Sea water can be distilled and used. It is a process which requires huge distillation plants and cost a lot of

money. So, the cost of getting pure water from sea water will be very high. When we have other sources

for obtaining water, it is better to use them. In places like Gulf countries where fresh water is scarce, the

sea water is the main water source hence; they distill seawater and use it.

2. When the temperature of a solution is increased, its solubility will also increase. So, the solutions will

become unsaturated with increase in temperature.

3. Put some of the white powder in water and mix well. If it dissolves, it is salt. If it does not dissolve and

remains suspended, it is chalk.

4. Pebbles can be picked with hands. Add a little water in the grass and sand mixture. The grass float on the

surface can be removed and sand settles down which can be easily taken out.


Change

The Sawing of a piece of wood.The melting of ice candy.Dissolved sugar in water.The cooking of food.The ripening of a mango.Souring of milk.

S.No.

1.2.3.4.5.6.

Can be reversed (Yes/No)

NoYesYesNoNoNo

Chapter-6 : Changes Around Us



1. physical 2. chemical 3. reversible 4. chemical

5. fast 6. irreversible 7. physical 8. chemical

9. irreversible 10. size 11. common


1. True 2. True 3. False 4. False 5. True 6. False

7. True


1. a. v b. i c. iii d. vi e. ii


1. c 2. a 3. c 4. b 5. a 6. c 7. a 8. c 9. c

NCERT Questions

10. b 11. a 12. d 13. d 14. d 15. c 16. d

E. Name them.

1. Changes in the colour, phase and temperature of a mixture are some of the indicator that a chemical reaction a has taken place.

2. a. Physical change b. Physical change c. Chemical change

d. Physical change e. Physical change f. Physical change

g. Physical change h. Chemical change i. Chemical change

j. Physical change k. Physical change l. Chemical change

m. Chemical change n. Chemical change o. Physical change

p. Physical change



1. Days and nights are caused due to the rotation of earth.

2. Increase in temperature causes ice to melt.

3. Water boiled in a pan changes into steam.

4. Irreversible changes are changes in which we cannot get the original substance back.

5. A chemical change is defined as a change in which a change in properties of a substance is caused. A new substance is formed as a result.

NCERT Questions

6. The only reversible change is the melted wax. When you let the melted wax cool down it turns back into solid wax. You could reshape this wax into a new candle.

7. It is a reversible change.

8. The heat will expand the atoms of the cap which will make it easier to pop open the cap.

9. Yes by unfolding the skirt the change can be revered.

10. No, it cannot be reversed it is an irreversible change.

11. Some, change are listed in the following table. For each change, write in the blank column, whther the change can be reversed or not.



12. By erasing the drawing we can undo the change. For example if we draw using a pencil we can erase the drawing using an eraser. Then it is a reversible change. But we draw using a pen it cannot be erased. Then it is an irreversible change.

13. Plaster of Paris is an irreversible and chemical change because plaster of Paris has a property of setting into a hard mass on getting mixed with water due to the formation of a new compound. The hard mass cannot be converted back into the previous Plaster of Paris. Hence, it is an irreversible chemical change.

14. Due to water the cement hardens and its composition changes. Chemical changes in general are irreversible changes. Since it is a chemical change it cannot be reversed.


1. Breaking of glass only changes the shape and size, but the glass remains same in its form and maintains its properties. So, it is a physical change.

2. Reversible Irreversible

(i) Evaporation of water (i) Cooking Rice

(ii) Compression of a spring (ii) Burning of coal

3. No, burnt paper cant be obtained in its original form.

4. Rusting of iron is a chemical change since iron changes to iron oxide and it can't be reversed.

5. Curdling of milk is a chemical change since the milk loses its texture, taste and properties, it is irreversible.

6. Inflating a balloon is a physical change since deflating the balloon will bring it back in its original form. The balloon does not change in its form or property.

NCERT Questions

7. We can reverse it by the following methods:

a. condensation, b. evaporation, c. freezing, d. Curdling

8. a. reversible, b. reversible, c. reversible, d. irreversible,

e. reversible f. irreversible g. irreversible

9. Tearing paper is a simple physical change and reversible change; you are taking a whole and dividing it ... is still a piece of paper. Paper recycling is the process of turning waste paper into new paper products. It is also a physical change and reversible change.

10. 1. Reversible changes: Changes that can be reversed is called reversible changes. Example: water changes into ice on cooling, wax change into liquid on heating, blowing of balloon

Irreversible changes: Changes that cannot be reversed is called irreversible changes. Like Milk change in to curd, iron changes to rust, burning of paper, cooking of food, growth of plant and animals, weathering of rocks, wear and tear of tires.

H.Long answer questions.

1. Water exists in solid, liquid as well as gaseous states. Water can change from one state to another. At normal room temperature, it is liquid. When it is heated or when energy is given it turns into vapours and when it is cooled, that is, energy is taken away from it, it turns into a solid state.

2. Physical changes: Changes in which physical properties like shape, size and state changes without formation of new substance is called physical changes. It is a type of reversible changes. e.g. Melting of wax, solution of sugar and water, boiling of water, expansion of iron on heating. Chemical changes: A change in which new substance is formed is called chemical changes. it cannot be reversed .Burning of paper, growth of nail, rusting of iron etc.

3. Reversible changes: Changes that can be reversed is called reversible changes. Example: water changes into ice on cooling, wax change into liquid on heating, blowing of balloon .Irreversible changes: Changes that cannot be reversed is called irreversible changes. Like milk change in to curd, iron changes to rust, burning of paper, cooking of food, Growth of plant and animals, weathering of rocks, wear and tear of tires.

4. Cooking food is a chemical change. The chemical molecules in the raw food undergo a chemical change

when heated and the cooked food has new taste, texture and chemical composition. So, the change is

irreversible.

5. Breaking of glass is a physical change. The size and shape of glass undergoes a change, but its

properties remain unaffected. So, it is a physical change.


6. All physical changes are not reversible. Most of them are, but certain changes like breaking of glass, breaking of a ceramic cup are changes in which we can't bring the same glass or cup back to its original form. In other words, they can't be reversed, though they are physical changes.

7. When a candle burns, the fuel present in wax is burnt to give heat and light. That is a chemical change. When the heat produced melts the surrounding wax it flows and solidifies later, on cooling. That is a physical change. So, while burning, some part of the wax undergoes chemical change and some part undergoes physical change.

8. Tearing of paper is not a chemical change since paper doesn't undergo any change in its chemical properties. But since we can't get the paper in original form it is reversible change.

9. A raw potato has starch, a hard texture and bland taste. When boiled, it becomes soft, sweetish in taste and the starch is changed to sugar. So, it is a chemical change.

NCERT Questions

10. a. wax change into liquid on heating, b. Burning of paper, c. water changes into ice on cooling, d. solution of sugar and water, e. Rusting of iron .

11. The shaping of clay into a pot is a reversible change but baking the pot in oven is an irreversible change.

12. Examples of reversible changes-water changes into ice on cooling, wax change into liquid on heating, blowing of balloon, expansion of iron on heating.

13. Examples of irreversible changes-milk change in to curd, Iron changes to rust, burning of paper, cooking of food, growth of plant and animals, weathering of rocks, wear and tear of tires.

14. Change b)-rolling the dough can be reversed into a dough again

15. Activities which can be reversed-a, c, d, e

Activities which cannot be reversed-b, f, g, h

I. Give reasons.

1. A change in state (solid to liquid, or liquid to gas, or solid to gas, etc.) is a physical change because the chemical composition of the material does not change. It is still the same substance chemically. For example, ice and water and steam all have the same chemical formula: H O.2

2. We need to study the change around us as the matter is changing rapidly so we have to keep the desirable changes happening.

3. The reason telephone wires sag from telephone poles on a hot day is because of thermal expansion of the copper wiring. The atoms within the wire are vibrating faster because they're at a higher temperature. The more energetic vibrations expand the size of the wiring.

4. Burning a candle involves both physical and chemical changes. To burn the wick involves a chemical change because the wick is burned to something irreversible. To burn the wax involves a physical change because the vapour wax can be condensed to form wax again.

5. Cooking is a chemical change because heat is going in and it is changing texture. And we cannot uncook the already cooked thing. It is also physical when you are not producing a new substance. Ice into water and water into steam are physical changes of state.

J. HOTS questions.

1. In winter, water flowing in pipes freezes due to low temperatures. The frozen water (ice) expands in volume as compared to the same quantity of water. So, frozen ice applies pressure on the pipes and causes bursting of the pipes.

2. A rubber tyre is placed in hot water to let it expand so that it can be easily fitted over the wheel. On cooling, it contracts and fits tightly over the wheel.

3. Dissolving sugar in water is a reversible and physical change as sugar can be obtained back by applying a physical method called evaporation.

4. Not all physical changes are reversible. Some physical changes like melting of ice are reversible whereas breaking of glass is a physical change but it is irreversible, so physical changes may be reversible or irreversible.

5. Tearing of paper is a physical change because no new substance is formed, as the paper's colour will be the same.

Chapter-7 : The Living Organisms and their Surroundings



1. habitat 2. environment 3. biotic,abiotic 4. abiotic components

5. Air,soil,water 6. desert 7. moist skin 8. salt

9. broad,narrow 10. Whales,dolphin 11. air cavities 12. adaptation

13. predator,prey 14. sweat,dung,urine 15. float 16. long,hollow

17. photosynthesis 18. polar 19. conical 20. life cycle

21. gum

NCERT Questions

22. adaptation 23. terrestrial 24. aquatic 25. abiotic

26. stimuli 27. abiotic 28. adaptation


1. True 2. True 3. True 4. True 5. True 6. False

7. False 8. False 9. False 10. False 11. False 12. False

13. False 14. False 15. False


1. a. v b. iv c. i d. ii e. iii


1. d 2. b 3. b 4. a 5. d 6. c 7. b 8. c 9. c 10. a

11. d 12. d 13. a 14. d 15. a 16. d 17. c 18. d 19. d 20. a

21. d 22. b 23. a

E. Name them.

1. Community 2. Respiration 3. Stomata 4. Abiotic

5. Pondweed 6. Sensibility



1. Transpiration.

2. Green plants make their own food. So they are called autotrophs.

3. Lotus and lily remain fixed to the pond bed.

4. Polar bears and frogs sleep throughout winter months.

5. Mountain goat and yak can survive harsh mountain climate.

6. Plants which don't reproduce by seeds are rose and sugarcane.

7. Camouflage is the ability of an organism to merge with the environment and become invisible.

8. Pine and cedar grow on high mountains.

9. Photosynthesis is the process in which plants give out oxygen.

10. a. Fish – lay eggs, b. Cow – give birth to its young ones, c. Dolphin – give birth to babies

11. Locomotion is the ability to move under one's own power, so locomotory organs are body organs used to

create that motion.

12. Phototropism focus on the directional growth of something to a light source, where geotropism focuses

on the direction against a light source. Phototropism is movement of shoot towards light and geotropism

is the movement of roots towards gravity.

13. An autotroph (or producer) is an organism that makes its own food from light energy or chemical energy

without eating. Most green plants, many protists (one-celled organisms like slime molds) and most

bacteria are autotrophs. Autotrophs are the base of the food chain.

14. The primary consumer is the first consumer that consumes energy in a food chain. Since plants produce

the sugars that are used for energy, the things that eat them are the closest to consuming the energy -

therefore, they are the primary consumers. ®Jiwan Science CCE Question Bank Answer Key-6/23


15. Respiration is the process by which food is oxidized to release energy. It is a biomedical process that

occurs in most known living organisms and may involve taking in of oxygen. In plants, it occurs during

daylight hours.

NCERT Questions

16. Habitat is the natural place where a living thing lives. It is an environment with suitable condition for an

organism to live. It could range from a small pond to a forest.

17. a. Adaptation b. Excretion c. Stimuli d. Reproduction

18. a. grassland b. pond c. mountain d. desert

19. Terrestrial – grassland and rice field, Aquatic – pond and ocean


1. Habitat is a place where an organism lives, breeds and flourishes.

2. Hibernation is a long winter sleep that some animals undertake when the weather is too severe. In

animals like lizard it helps to conserve energy.

3. Adaptation is development of features which help an organism to live in a particular environment. For

example, desert plants have their leaves turned into spines to help them to conserve water. Aquatic

plants like lotus have wax coated leaves to stop water entering them.

4. The mountain goat has strong hooves, which helps it to climb steep mountains.

5. Tall grasses have flexible stalks and strong roots to withstand windy conditions and to anchor it firmly to

the soil.

6. Whales and dolphins breathe in air through blow holes located near the upper part of their heads.

7. Oxygen is breathed in to oxidize food to release energy.

8. Plants are always seen moving towards sunlight and their roots towards the earth. It proves that plants

show movement. The sunflower is an interesting example too. The flower always keeps moving in the

direction of the sun.

9. Autotrophs are plants algae or some bacteria that make their own food molecules from the process of

photosynthesis or chemosynthesis while Heterotrophs whose examples are animals, fungi, protozoa,

slime molds, some bacteria, must get their food molecules from eating another organism or through

absorbing the nutrition from them.

10. Deer have eyes at the sides to help them have a wider view of the surrounding. Since they bend down to

graze, they can easily become a prey to the predator so their eyes on the sides protect them. Lions are

animals which hunt for their prey, kill them, take them to their territory and then feed. So they don't face

dangers while feeding. Their eyes are helpful in focussing on the prey.

NCERT Questions

11. The cactus is adapted to living in the desert because of its stem that has the ability to store large amounts

of water. It has a waxy layer that aids in reducing water loss.

12. Non-living things– plough, sewing machine, radio, boat.

13. A bus or a car which shows movement and consumes energy.

14. Following things were never part of living beings: soil, electric bulb, salt.

Following are the things which were once part of living beings:

• Butter: Obtained from milk from dairy animals.

• Leather: From animal skin of buffaloes, cows etc.

• Wool: From hair of sheep and goat.

• Cooking oil: seeds of plants (e.g. mustard) or by grinding whole plant (e.g. olive).

• Apple: fruit from apple tree.

• Rubber: Latex of rubber tree.

15. Paheli can grow many more roses by stem cutting.

16. Desert snakes stay deep inside the sand in burrows to survive the heat of the sun during the day. They

come out during the night when it is cool.


17. a. Some aquatic plants are totally submerged in water and the part of such plants grow under water. All

parts of such plants grow under water. The roots are much reduced in size and their main function is

to hold the plant in place. The stems of these plants are long , hollow and light. The stems grow up to

the surface of the water while the leaves and flowers , float on the surface of the water . Eg water

Hyacinth. Some other aquatic plants have narrow and thin ribbon like leaves. These can bend in the

flowing water. These leaves can bend in the flowing water. Such leaves are highly divided , through

which water can easily flow without damaging them.

b. In some other cases, like the lotus, require much sunlight. Their leaves are wide and disc shaped.

Their stem and leaves have a waxy coating. This coating helps the leaves and stem from getting

wet, so they float on the surface of the water.

18. a. Camels have long legs which help to keep their bodies away from the heat of the sand. The animal's

wide toes stop it from sinking in the sand and function just like snowshoes.

b. The fully-webbed hind feet of the frog help them to swim in water. They breathe through their moist

skin when in water.

c. Whales and Dolphins breathe in air through blowholes located near the upper part of their heads.

They come near the surface of water to breathe in air. They can breathe in water without breathing for

a long time.

19. The leaves in the desert plants are either very small or are reduced to spines. This helps in reducing loss

of water from the leaves through transpiration. The stem becomes fleshy and green. It performs the

function of the leaf i.e., Photosynthesis. The stem stores water in it. It also has a waxy coating which

helps to retain water.

20. Deer has long and sharp ears to hear the movements of its predators. it has strong legs and is an

excellent runner. It has eyes on either side of its head which allows it to look in all directions for danger. it

moves in herds to protect itself from danger.

21. a. desert plant, b. aquatic plants, c. mountainous plants,

d. mountainous plants, e. mountainous plants, f. aquatic plants.


1. (a) All living things show movement from place to place.

(b) They respire.

(c) Need food to survive.

(d) Respond to external stimuli.

(e) Can reproduce and increase their species.

(f) Have a fixed lifespan.

2. (i) Camel:

(a) Has a hump to store fat.

(b) Long eyelashes to protect eyes from sun and sand.

(c) Light colored skin to reflect sunlight.

(ii) Lotus:

(a) Long, hollow, light weight stem.

(b) Waxy coating on leaf to prevent water stagnation.

(c) Stomata on the upper surface of leaves.

(iii) Polar Bear:

(a) Thick layer of fat under the skin.

(b) Hibernation during winter.

(c) Thin fur on the skin.

(iv) Pine tree:

(a) Leaves are needle like.

(b) Tall, straight and conical shaped.

3. The happenings in our surrounding which make us respond to them is a stimulus. The immediate

reaction to the stimulus in an organism's body is the response. For example, when we hear blaring

sound, we close our ears. The sound is the stimulus and the closing of the ear is the response. All animals

respond to stimuli. Their sense organs help in this. Some plants respond to stimuli like the touch me not

plant. When we touch the leaves they close. Stems grow towards light and roots grow towards earth.

Sunflower keeps moving towards the sun.

NCERT Questions

4. A bus or a car which shows movement and consumes energy (petrol).

5. Lions have eyes that are well-adapted for use under very low light which helps them hunt for food at night

for their survival. They also have a well-developed sense of smell which they can make territories by

means of scent deposits.

I. Give reasons.

1. Producers are organisms that have the ability to convert solar energy to chemical energy. Only plants

have this capability, they can trap light which is then used in photosynthesis to produce food. Animals and

other organisms cannot use solar energy directly, hence plants produce food/energy for them.

2. Bacteria and fungi are called decomposers as they chemically breakdown dead organisms and change

them from complex organic substances to simple inorganic substances that mix with the soil, to obtain

energy for themselves. As their 'decompose ' waste and leave no residue, they are called decomposers.

3. The reason the eyes of a lion are set in the front of his head rather than on the sides are because he is a

predator. Prey needs to see a much larger view to keep from being eaten, but the lion needs only to focus

on his prey at the front.

4. Yes, all living organisms show adaptation.

Adaptation is the evolutionary process whereby a population becomes better suited to its habitat. This

process takes place over many generations, and is one of the basic phenomena of biology.

The term "adaptation" may also refer to a feature which is especially important for an organism's survival

and reproduction. For example, the adaptation of horses' teeth to the grinding of grass, or their ability to

run fast and escape predators. Such adaptations are produced in a variable population by the better

suited forms reproducing more successfully, that is, by natural selection.

5. Animals adapt so that they can survive and thrive where they live. They use their physical features to help

them get hold of food, keep safe, build homes, withstand weather as well as attract mates.

J. HOTS questions.

1. Animals like lizards, frogs, etc., eat a lot before hibernating in order to store a lot of fat to be used during

their hibernation. The body needs minimum amount of energy to help the organism to survive and that is

drawn from the stored food.

2. Oxygen is very essential for survival of all aquatic organisms and they can get it only in a dissolved form.

If we spray some oil or kerosene on the surface of a pond, the animals normally inhabiting the pond will

start perishing. That is why, pouring some kerosene on a stagnant pool of water helps to eradicate

mosquito menace. Oil spills on seas and oceans destroy aquatic life by preventing oxygen from

dissolving in water. Rapid multiplication of plants like water hyacinth prevents survival of any other form

of life in ponds and lakes since they use up all the oxygen dissolved.

3. No, there are certain mammals in water like dolphins and whales which have lungs and they take oxygen

from air by coming on the surface of water.

4. Animals eat before going in for hibernation to built fat so that when they wake up most of the fat is gone

and they will be back to their usual self.


Chapter- 8 : Getting to Know Plants



1. water, minerals 2. tap 3. stamen, pistil 4. lamina

5. anther 6. stigma 7. venation

NCERT Questions

8. calyx 9. ovary, ovules 10. filament, anther 11. bud


1. True 2. False 3. False 4. True 5. False 6. True

7. False 8. True 9. False 10. True 11. True 12. True

NCERT Questions

13. False 14. False 15. True 16. False 17. False 18. False

19. False 20. False 21. False 22. False


1. a. iii b. ii c. iv d. i


1. d 2. b 3. c 4. d 5. b 6. b 7. d 8. a 9. c

NCERT Questions

10. a 11. d 12. b 13. d 14. b 15. b

E. Name them.

1. Desert plants(Cactus) 2. Climbers(Grapevine) 3. Insectivorous plants(Venus Fly trap)

4. Radish 5. Banyan 6. Pea plant

7. Seed 8. Fruit

NCERT Questions

9. a. Herb, b. Root



1. The process of evaporation of water through the stomata of leaves is known as transpiration.

2. Tendrils give extra support to the plant by coiling around objects.

3. a. Thin thread like structures arising from the stem, which give support to the plant are stem tendrils. b)

Chlorophyll: The green colour pigment present in leaves which helps in photosynthesis. c)

Venation: The arrangement of lines (veins) in a leaf. d) Xylem: The tubules through which water and

minerals are conducted through the plant. e) Phloem: The tubules through which food prepared in

the leaf is distributed to other parts of a plant.

4. Creepers are plants with weak stems. They can't stand upright and spread on the ground. eg., pumpkin,

water melon.

5. Prop roots of banana tree are modified roots.

6. (a) Wheat (b) Rose (c) Prop root (d) Grapevine

7. In plants like banana, leaves have veins running parallel to each other along the length of the leaf. This is

called parallel venation.

8. Transference of pollen to stigma of the flower is pollination.

9. Sepals protect a flower in bud form.

10. Plants give out oxygen during photosynthesis.


entiremargin

midrib

petiolemargin

petiole

lobe

sinus


11. Plants prepare food in the form of sugar.

12. Pistil is divided into style, stigma and ovary.

13. Solution of iodine is used to test starch.

NCERT Questions

14. a. Leaf

b. Tap root

c. A flower

15. Money plant, climbers.

16. Tulsi, coriander, china rose.

17. Parallel.

18. Yes, if a plant has leaves with parallel venation it will have fibrous root system a characteristics of

monocot plants but if the leaves have a reticulate venation the root system it will have tap root system a

characteristics of dicot plants.

19. Flowers.

20. Joined sepals: Rose, Lotus.

Separate sepals: China rose, Mustard flower.

ROOTROOT

primary root

lateral rootroot hairs

root tip

root cap

pollen

petal

anther

filamentstamen

stigma

style

ovary

carpel

ovule

stemreceptacle

sepal



1. The main difference between tap roots and fibrous roots is in their features. The tap roots are mostly one

main root that goes deep into the ground. On the other fibrous roots are many and spread shallowly on

the ground surface. Examples of tap root system include carrots, beets among others. Fibrous roots are

those that have many roots growing from the stem examples are onions, tomatoes among others.

2. There are four types of leaf veneration. These are: dichotomous, pinnate, palmate and parallel venation

systems. These vein systems are the pathways of liquids and nutrients to leaf cells.

Monocots have parallel venation but dicots have reticulate venation.

3. In plants like banyan tree, roots grow down from its branches to give extra support to the huge tree. Such

roots are called prop roots. They are pillars supporting a building.

4. (i) Roots fix the plant firmly to the soil.(ii) Roots absorb water and minerals present in the soil and

transport to other parts.(iii) Roots bind the soil and help in soil conservation.

5. In a cactus plant, the leaves are reduced to spines to prevent the loss of water from its surface.

6. Stem and leaf tendrils are thread like structures growing from the base of the leaf which give extra

support to the plant. In grapevine, gourds, etc., stem tendrils are seen. In peas, beans, etc., leaf tendrils

are seen.

7. (i) Pollination: The transference of pollen grains from the anther to the stigma of the flowers is

pollination.(ii) Transpiration: The loss of water from the leaves of a plant is through stomata and is known

as transpiration.(iii) Photosynthesis: Preparation of food by the leaves with the help of sunlight, water

and carbon dioxide is photosynthesis.

8. Leaves are modified into spines in desert plants. They are modified into tendrils in plants with weak

stems. In carnivorous plants like pitcher plant and venus fly trap, the leaves are modified into insect

traps.

NCERT Questions

9. Function of stem.

(a) Give support to the plant.

(b) Conducts water and minerals from roots to leaves.

(c) Conducts food from leaves other parts of the plant.

10. 1. Sepals 2. Petals 3. Stigma 4. Anther 5. Style

6. Androecium 7. Gynoecium

11. Leave produce food. the process is called Photosynthesis.

12. He did not bleach the leaf in alcohol..

13. No it will not show any colour as photosynthesis has not taken place in that leaf. Starch is formed as a by

product of the photosynthesis and starch with iodine gives a blue black colour.


1. Pollination is a very important phenomenon in the reproduction of a plant. Pollination helps in the

formation of fruits and seeds. The seeds are carriers of the fertilized egg which can grow into a new plant.

So, pollination is the most important step in the process of fertilization.

2. Through transpiration a plant gets rid of excess water. The loss of water from the leaves creates a pull for

more water carrying minerals from the soil to enter the plant.

3. To prove that sunlight is necessary for photosynthesis: Take a potted plant, select a leaf and cover it well

with black chart paper, and seal tightly. Leave the plant in the sun for two days.Then pluck an uncovered

leaf and the covered leaf, and test both of them for starch. You'll observe that the leaf covered with black

paper will not show the presence of starch.

4. Mangroves are found in marshy areas. So, the roots find it difficult to breathe since they don't get enough

air. In these plants, the roots come out of the soil to breathe as a modification.


5. The reproductive structures of a flower are the stamen and pistil.

Stamen: Thread like structures are the male reproductive parts of the flower. It has a thin, thread like

structure known as filament with a bag like head called the anther. The anther contains the

pollen grains which are reproductive cells.

Pistil: It is the female reproductive part of the flower. It is the tube like structure in the centre of the

flower. The upper part is the style and the topmost part of it is the stigma. The lowermost

swollen base is the ovary.

6. To demonstrate the transportation of water in a plant: Take a branch of money plant and place it in a

beaker half filled with water. Add a few drops of red ink. Let the plant stay in the beaker for a day or two.

Observe the lines in the leaves. You will see streaks of red colour. It proves that water in which red ink is

added has been absorbed by the plant.

NCERT Questions

7. a. Root b. Leaves c. Flower d. Stem

8. Parallel venation – Grass, Peepal

Reticulate venation – China rose

9. a. 1. Petiole 2. Midrib 3. Lamina 4. Vein

b. Reticulate venation. c. Parallel venation.

10. a. Transpiration. b. On a bright sunny day or a cloudy day.

c. A bright sunny day tiny droplets of water. d. Perform the activity in sunlight.

11. a. Anther is a part of the stamens. b. The visible parts of a bud are the sepals.

c. Lateral roots are present in a tap root. d. Leaves also perform the function of transpiration.

I. Give reasons.

1. Yes a small Mango plant is a herb but upon growing it has a thick, hard, brown stem and is big and called a

tree herbs.

2. The leaves of cactus are modified to sharp spine to reduce the area of water loss when sweat.

3. Transpiration helps a root to pull more water to compensate the loss of water from the leaves through

stomata.

4. Because photosynthesis takes place at the leaves, with help of chlorophyll (which is why leaves are

mostly green), sun, CO and water, at the leaves the plant produces glucose which is mainly the food of 2

the plant.

5. Although they are called banana trees, the plant that the banana fruit grows on is actually an herbaceous

plant, not a tree. That is because it lacks woody tissue. A banana grows from a corm. A tree has a trunk. A

banana has a stem which can die back and regrow so it is an herbaceous plant not a tree.

J. HOTS questions.

1. Watermelons, like other types of cucurbits, have a sprawling growth habit and stretch out across the

ground. The watermelon vine's sprawling growth habit make it a creeper, but you can provide support for

watermelons and grow them vertically to save space. Creeping plants are vines that send runners out

along the ground and need plenty of room to grow. Creeping plants have weak stems and cannot grow

vertically or climb without support. These plants grow fiber like roots at the spots or nodules where

leaves grow. These stems are known as prostrate stems, but they can climb if provided with sturdy

support system. Although watermelon plants are vines, they cannot climb without a strong support.

Watermelons become heavy, which can topple the average trellis, so supporting and training

watermelons to grow vertically instead of horizontally can be a chore.

Chapter-9 : Animals : Form and Movement



1. bone marrow 2. 305,206 3. Exo 4. Vertebra

5. Brain case, facial bones 6. lower jaw 7. exoskeleton, endoskeleton

8. organ system 9. 33 10. 14

11. collar bone, shoulder bone 12. tibia, fibula 13. hinge joint

14. Cartilage 15. tendons 16. foot

17. water resistance

NCERT Questions

18. movement 19. skeleton 20. hinge 21. muscles


1. False 2. True 3. False 4. False 5. True 6. True

NCERT Questions

7. False 8. False 9. True 10. True


1. a. vii b. vi c. v d. i e. ii f. iv g iii

NCERT Questions

2. a. iv b. i c. v d. iii e. ii

3. a. iii b. v c. iv d. ii e. i


1. b 2. c 3. a 4. c 5. c 6. b 7. c 8. c

NCERT Questions

9. a 10. c 11. c 12. a 13. c 14. a

E. Name them.

1. Invertebrate 2. Streamlined 3. Skeleton system 4. Bone marrow

NCERT Questions

5. Ball and socket joint 6. Bones 7. Human skull 8. Muscles

9. Rib cage 10. Skeleton 11. Ribcage 12. Pivot joint

13.Cartilage



1. Hinge joint is present in the elbow.

2. Vertebrae are small bones of the backbone.

3. Spinal cord is protected by the backbone.

4. The lower jaw is the only movable bone in the skull.

5. Biceps and triceps help in moving our arms.

6. 10 pairs of ribs are attached to the breast bone.

7. Exoskeleton is present in earthworm.

8. Human skull is connected to the spine through the collar bone and shoulder blade.

9. Calcium and phosphorous make our bones hard.

10. Biceps and triceps control the movement of our arms.

11. The main difference between vertebrates and invertebrates is that invertebrates do not have a backbone

or a spinal column. Examples of animals considered to be invertebrates are reptiles such as snakes,

lizards and arachnids such as spiders and millipedes.



12. Frogs have an endoskeleton. They actually have bones that form a skeleton around which their body is

built.

13. Birds are 'warm-blooded' vertebrates, with forelimbs modified to wings, and skins covered with feathers.

NCERT Questions

14. In a human body, a ball-and-socket joint is generally a joint that can rotate within a socket. It is a freely

moving joint where a sphere found at the head of a bone fits into a cavity, which is rounded, in the other

bone.

15. Lower jaw.

16. Elbow cannot move backward because it has hinge joint which allows only back and forth movements.

17. Gliding joint

18. a. ball and socket joint, b. pivot joint, c. hinge joint


1. A group of similar cells performing a specific function is called a tissue. e.g., bone tissue, muscular tissue.

2. Bone marrow is the soft spongy substance present in the hollow centre of long bones of our arms and

legs. Bone marrow is the place where new blood cells are continuously getting manufactured.

3. Heart is protected by ribcage. Eye socket in brain case protects the eyes. Backbone protects the brain

and spinal cord.

4. Out of the12 pairs of ribs in the rib cage, the last two pairs, which are not joined to the breast bone, are

known as floating ribs.

5. If the backbone were a simple long bone, we would have a stiff back which could not bend or be twisted.

6. a. Tendons are tough connecting bands that bind the bones to the muscles. Ligaments connect one

bone to another.

b. Exoskeleton is present in the outer body surface. e.g., feathers in birds, scales in reptiles, etc.

c. Hinge Joint: The kind of joint present in elbows, fingers, knees and toes which allows movement

only in one direction. Gliding joint allows side to side as well as backward and forward movement as

in wrist, ankle, and between the two vertebrae of the backbone.

d. Bones are hard and are made of collagen, calcium, phosphorous and other minerals. They are hard

from outside and spongy from inside. The long bones are filled with a soft substance known as bone

marrow. Cartilage is a flexible connective tissue found in many areas in the bodies of human beings

and other animals. It is not as hard and rigid as bone but is less flexible than a muscle. The tip of our

nose and pinna of the ear are made of cartilage.

7. Joints are functions where bones of our body are connected to each other, making it possible for us to

bend these parts.

The four joints are:

a. Hinge joint b. Ball and socket joint

c. Pivot joint d. Gliding joint.

8. Earthworm moves by contractions of its body. To move, it first extends the front part of the body keeping

its rear part fixed to the ground. Next, it fixes its front part and shortens it, thus pulling the rear part

forward. This expansion and contraction of muscles helps the earthworm to move.

Snake: The snake uses its long and flexible backbone to curve its body into loops. Each loop pushes

against the ground and gives a forward push to the body so snake moves very fast but in loops.

Snails: The snail has a thick structure called a foot. It is made up of strong muscles. It produces a series of

wave like movements that push the snail's body forward.


NCERT Questions

9. The streamlined body in a fish helps them to glide along in the water and reduce the water resistance.

10. a. Digestive system: Helps in digestion and assimilation of food that we eat.

b. Circulatory system: Helps to pump and transport blood through our body parts.

c. Excretory system: It works to eliminate wastes from our body.

11. Duck—creeping, kangaroo---jumping, horse---running, snail---crawling, snake—slithering,

fish—swimming, Human being—walking, cockroach---flying.

12. An X-ray is needed to confirm a broken ankle and help decide the appropriate treatment.

13. We can bend our elbow, knee etc because of joints.

14. a. Forward and backward movement only.

b. We would be able to move our head in all directions.


1. In this type of joint, one bone which has a ball like end fits into the hollow socket of the other bone. This

type of joint allows movement in all directions. e.g., in our shoulders, the humerus of the upper arm has a

ball like end. It fits into the hollow socket of the shoulder girdle and thus is able to move freely.

2. Hinge joint allows movement only in one direction like the hinges of the door. It is present in elbows,

fingers, toes and knees.

3. Pivot joint allows movement in all directions whereas gliding joint allows side to side, as well as backward

and forward movement. The joint that is found between the skull and the first two vertebrae of the spine is

a pivot joint which allows us to rotate our head and move it up and down and left and right. The gliding

joint is seen between the vertebrae of the back bone which glide over one another when we bend and

straighten.

4. The skeletal system is made up of a framework of bones. They:

(i) Provide support to our body.

(ii) Give shape to the body.

(iii) Protect our delicate internal organs like the brain, heart, lungs, etc.

(iv) They make all types of movement possible.

5. Fishes have backbone. Muscles are attached to the bones. The muscles that enable the fish to move are

found on either side of the backbone. These muscles contract on one side and expand on the other. This

moves the body from side to side in a zig-zag pattern pushing against water and this force moves the fish

forward. Earthworms do not have a backbone. They move by contraction and expansion of their body

muscles. They extend the front part of their body keeping the rear part fixed to the ground. Then it fixes

the front part and pulls the rear part forward.

6. Biceps and triceps are two sets of muscles which work in pairs. When we bend our arm the biceps

contract and it pulls the bones closer. When we straighten our arm, the biceps relax and the triceps

contract, in the straight position of the arm.

7. To move a part, at least two sets of muscles are required, which work in pairs. When one of the muscles

contract, the bone is pulled in that direction while the other muscle of the pair relaxes. When the

movement takes place in the opposite direction, muscles simply exchange actions.

8. a. i. Bones ii. Cartilage iii. Movement iv. Shape

v. Contraction vi. Organs vii. Muscles viii. Relaxation

b. Bones and cartilage, shape, movement, organs, contraction, relaxation, muscles.

NCERT Questions

9. The snake A will move very fast as the snake moves in loops pushing against the ground and loops give a

forward push to the body.

I. Give reasons.

1. Animals move to find food.

a. Escape predators.

b. Escape hostile conditions/find more habitable conditions.

2. Elbow joint is an example of hinge joint which allows movement back and forth. Therefore, we cannot

move our elbow like our shoulders.

3. Because contraction of one muscle and relaxation of other muscle leads to the movement of the joint in

one direction.

4. The skeleton of a typical bird is lightweight and strong–well suited to flight. The bones of birds are not

solid; they contain air and are supported internally by struts. The bill, too, is light and strong. Bones form a

strong and rigid frame for the chest cavity so it will not collapse during flight. The strong flight muscles are

attached to the large keel of the breast bone (sternum). Birds, such as emus and penguins, that do not fly,

have heavier bones.

The wing contains bones equivalent to those in the forelimbs of other vertebrates and to the human arm.

In birds, the sizes and shapes of the bones and the structure of the joints are suited to flight and to folding

the wing neatly against the body while resting. The bones that are equivalent to the human hand and

finger are joined and shaped in a way that gives strength to the outer wing.

J. HOTS questions.

1. Our elbows have hinge joint between the bones which move only in one direction like the hinges of a

door. So, the backward movement is not possible.

2. The snake moves by making loops which push against the ground to move forward. A smooth ground

with low friction will not be able to give the necessary grip so it will find it difficult to slither on smooth

grounds.


Chapter-10 : Measurements and motion



1. Length, mass, time 2. elbow, tip of the middle finger 3. System International d 'Unites

4. Kilogram 5. Joule 6. thread

7. rectilinear 8. axis

9. planetary motion, hands of a clock

NCERT Questions

10. 1000 11. rotational motion 12. periodic motion

13. in, straight 14. Meter 15. 100cm

16. 5000m 17. Circular motion 18. Periodic motion


1. False 2. False 3. True 4. False

NCERT Questions

5. False 6. False


NCERT Questions

1. a. iii b. ii c. i


1. a 2. d 3. b 4. a 5. a 6. c 7. d

NCERT Questions

8. d 9. d 10. c 11. b 12. d 13. b 14. c 15. c 16. d


E. Very short answer questions.

1. Change of positioning of an object with reference to a stationary object.

2. 100 cm = 1 m.

So, 165 cm = 1.65m

3. a. Meter b. Kilometer c. Gram d. Kilogram

4. Children playing in a park will include many different kinds of motion—like periodic motion on a swing,

random motion in hide and seek game, etc., riding a bicycle includes rotational motion and linear motion

5. In CGS system unit of mass is gram, unit of length is centimeter and unit of time is second.

6. SI unit stands for Systeme International d'unites

7. The materials we buy in the market like the groceries, milk, milk products, cloth, gold, silver, etc., have to

be measured in order to have a monetary value fixed to it. So we need a standard measurement. The

temperature of many objects including the human body is essential in chemical reaction, cooking and

health analysis. We need to measure temperature.

8. In olden days before standards of measurement were formulated, people used body parts as standards

for measurement. The handspan was the length between the tip of the thumb to the tip of the little finger.

Footspan referred to the length of the human foot.

9. 1kilometer = 1,00,000 cm.



NCERT Questions

10.1 millimetre < 1 centimetre < 1 metre < 1 kilometre

11. a. The motion of man on a straight road.

b. The motion of wheels of a car.

c. Motion of blades of fan is an example of circular motion.

d. a circular orbit and a rocking chair.

F. Short answer questions.

1. In everyday life, we need to quantify whatever we buy—like fruits and vegetables, groceries, medicines,

milk, oil, etc., so that we can attach a monetary value. Similarly, length, temperature, pressure and many

more physical quantities should be measured for carrying out scientific analysis. So the need for

accurate measurement arises.

2. In olden days length was measured in footspan, handspan or cubit, using body parts.

3. Standard units of measurement are accurate and dependable.

4. Riya should take the reading from the next digit that is clearly marked on the scale and the value of this

digit will have to be reduced from the final reading.

5. In rotational motion an object moves around an axis and its different parts move at a different speed. In

kinetic motion, an object repeats the motion at regular intervals of time. The entire object moves covering

the same distance in fixed interval of time.

NCERT Questions

6. Take a non-stretchable string or a thread and tie a knot at one of its ends.

• Place the knotted end of the thread at one end of the curved line.

• Holding the thread steadily with your fingers, and stretch it along the curved line until you reach the

other end.

• Now make a mark on the thread where it reaches the other end.

• Finally, place the thread along a metre scale and measure the length between the knot and the

marked point.

• This gives the length of the curved line.

7. d

8. 1m = 100cm and 1cm = 10mm

∴ 1.65 m = 1.65 x 100cm = 165cm

9. Since 1 m = 1 ÷ 1000km

∴ 3250m = 3250 ÷ 1000 = 3.250 km

10.33.1cm – 0.3 cm = 32.8 cm

11. A bicycle moves in a rectilinear motion. While a ceiling fan moves in a circular (Rotational) motion. They

move but the bicycle covers distance on the land while the fan moves around a fixed axis.

12.Since the tape is stretchable, its measurements will be inaccurate. Therefore we cannot use it as

measuring tape. While measuring a distance, we need to tell someone how much tape has been

stretched which is difficult to measure. It leads to incorrect measurements.

13.Rotation of the planets around the sun, oscillation of pendulum.

G. Long answer questions.

1. Ruler is a device used for measuring length.

(i) It is important that the measuring scale used is accurate, not broken or distorted, and the marking

should be clear.


(ii) The ruler is in contact with the object along its length.

(iii) In case, the starting point or zero mark is broken, the reading can be taken from the next digit that is

clearly marked on the scale and the value of their digit will have to be reduced from the final reading.

(iv) It is important to place one eye vertically above the measuring device.

2. To measure a curved line, we can use a thread. Take a long thread and tie a knot at one end. This marks the

beginning. By placing the thread with the knot at one point, pass the thread along the curved surface till the

end. Mark the end with a pen. Measure the length of the thread from the knot to the pen mark over a ruler.

3. The three kinds of motion are: (i) Translatory Motion (ii) Rotational Motion (iii) Periodic Motion

(i) Translatory Motion: The motion of an object that takes it from one place to another is called

translatory motion. e.g., a car moving on the road, a bird flying, a stone falling from a height, etc.

Translatory motion can be circular or rectilinear.

Circular motion takes place when an object moves on a curved path. When the motion is in a straight line,

it is said to be rectilinear motion.

(ii) Rotational Motion: The movement of an object around a fixed axis like the spinning of a top, the

rotation of a merry go round, the earth and a wind mill are examples of rotational motion.

(iii) Periodic Motion: The motion of an object that repeats itself at regular intervals of time is called

periodic motion.

4. The two types of translatory motions are:

(i) Rectilinear motion is the motion of an object along a straight line – e.g., movement of a car on a

straight road, movement of a train on tracks.

(ii) Circular motion: The motion of an object in a circular path in a closed loop e.g., the planetary motion,

movement of a carona circular road, movement of satellites in orbits, etc.

NCERT Questions

5. While travelling in the train we feel that the outside objects are calso moving. However, it is the position of

the train that is changing with respect to the objects outside. Thus it is

6. Motion of a bicycle is a rotatory motion. As the bicycle tyre moves around an axis, but the motion of a tyre

in which it moves around an axis and outside rim of the tyre moves at the different speed is rotational

motion. But the blades of electric fan rotate in circular motion. circular motion is a movement of an

object along the circumference of a circle or rotation along a circular path or a circular orbit . It can be

uniform , that is, with constant angular rate of rotation (and thus constant speed), or non-uniform , that is,

with a changing rate of rotation.

7. a. Cycle moves is rectilinear motion.

b. Wheel of a bicycle show circular motion.

c. The circular in a straight line.

I. Give reasons.

1. Standards of measurement are necessary for many different reasons. Science, medicine, and

engineering around the world use a standard measurement system to ensure that their results are more

precise and uniform. In social sciences, there are no standard units of measurement and the theory of

measurement is studied in pyschometrics and the study of the theory of conjoint measurement. Units of

measurements were one of the first tools invented by humans. Primitive societies used rudimentary

measures for many different tasks including making clothing, constructing buildings, and bartering food.

2. To make our measurements accurate we need subunits and categories.

3. A spinning top is a rotatory motion. A rotatory motion is not translatory motion because every point in the

moving object moves through a different distance in the same interval of time.

4. Motion of earth around sun is translatory motion where as motion of earth on its axis is rotatory motion.

When the earth revolves around the sun covering the same distance in an almost fixed period of time, it is

an example of periodic motion. When the earth moves along its axis the axis does not move, it is fixed

support making it a rotatory motion.

J. HOTS questions.

1. A rolling ball moves from one place to another showing translator motion. At the same time, it also keeps

rolling as it is in rotation.

2. While unscrewing a screw, we move the screw outward. It is translatory motion. The screw moves in

rotational motion with every turn we make and so it also has rotational motion.

3. A screw undergoes circular and rotational motion.

4. When measuring it is important that the measuring scaleor ruler used is accurate, not broken or

distorted, the marking should be clear. To ensure the correct usage of the measuring scale one has to

ensure that:

• The ruler is in contact with the object along its length.

• In case the starting point or zero mark of the scale is broken, the reading can be taken from the next

digit that is clearly marked on the scale and the value of this digit will have to be reduced from the final

reading.

• It is important to place the eye vertically above the measuring device.


Chapter-11 : Electricity and Circuits



1. dry cell 2. chemical reaction 3. negative, positive

4. key 5. electric circuit 6. metal, plastic

7. electric shock 8. 1.5 volts 9. battery

10. solar 11. fused 12. ISI

NCERT Questions

13. switch 14. two


1. True 2. False 3. False 4. False 5. False

NCERT Questions

6. True 7. False 8. False 9. False 10. True


NCERT Questions

1. a. ii b. iv c. i d. vi e. v


1. c 2. b 3. c 4. b 5. a 6. a 7. d 8. c 9. b 10. c

NCERT Questions

11. b 12. a 13. b 14. c 15. d 16. b 17. d

E. Name them.

1. Battery 2. Circuit 3. Filament 4. Good conductor

5. Terminal



1. Electric current can produce light, heat, sound, chemical and magnetic effects.

2. The thin metal wire is called the filament.

3. A dry cell is easy to carry around.

4. The two ends of a cell are anode and cathode.

5. Path of flow of current is called electric current.

6. In electric torch, electrical energy is converted to light energy.

7. A switch is used to open or close a circuit.

8. Electricity can pass easily through copper and silver.

9. Thomas Alva Edison invented the electric bulb.

10. Air does not conduct electricity.

NCERT Questions

11. In diagram A the cell will be used up very rapidly. The chemicals in the electric cell get used up very fast

and the cell will no longer produce electric current. It will stop working.

12. 1. Filament 2. Glass Mount

3. 3 and 4 are Terminals 4. Glass stem.




1. An electric current is the path provided for current to flow.

2. The flow of electrons from the negative terminal to the positive terminal of the circuit through a conductor

is called current.

3. The switch is in the 'ON' position, the circuit is closed.

4. When the dry cell is the source of electric current in a circuit.

5. Electricity used at home is generated by large generators far from the cities.

NCERT Questions

6. The handle of the screw driver acts as an insulator. It does not allow current to flow and circuit is still open.

Therefore the bulb does not glow in the arrangement.

7. The bulb will glow when circuit is complete i.e. one end of the wire from clip is connected to positive

terminal. Second end of the wire from the clip is connected to the bulb.

8. An electric switch is a simple device which is used to break or complete an electric circuit. Switches are

widely used in different electrical or electronic gadgets. A few are:

Toggle switches used in houses.

Pushbutton switches used in microwaves, water pump, mixer etc.

Joystick switches used in Video Games Controllers, Toy Cars etc.

9. No. An eraser is made of rubber which is a poor conductor of electricity. Therefore, bulb would not glow.

10. Since the object allows current to flow and completes the circuit. Due to this bulb begins to glow. It means

the object is a conductor of electricity.

11. Electricians need to touch copper wires or they may accidentally come in contact with live wires (wires

carrying current). Since human body is also a good conductor, electricians may get shock. Rubber is

good insulator. To prevent themselves from electric shock or flow of current, the electricians use rubber

gloves while repairing.

12. Without the help of insulators, the use of electrical tools like pliers and screwdrivers is impossible. Wood

and plastics are insulators and help in avoiding direct contact with electric current. When electricians

touch these live electric wires with the tools covered with plastic and wood, current does not flow in their

body avoid any accident.

13. The electric bulb has two terminals, both the wires are connected to the one terminal of the bulb. Current

will not flow from the bulb and it will not glow. To make glow, the two wires should be connected to each

terminal of the bulb, as shown below.

(–ve)

(+ve)


14. The bulb will glow when circuit is complete i.e. one end of the wire from clip is connected to positive

terminal. Second end of the wire from the clip is connected to the bulb.

15. Electric current flows only when there is an unbroken path for it to flow from one terminal to the other. It

will also not flow if the wires are not connected properly to both the terminals.

16.

17. Rechargeable batteries work by doing a process that is the opposite of what happens during the

chemical process when a battery is discharged. In order for this to occur, the battery must regain the

electrode materials that are lost when the battery discharges. Special are used to replace these

materials, which allow the battery to be used again and again. Many people prefer using rechargeable

batteries, as they can save a lot of money instead of purchasing new batteries over and over again.

18. A series circuit is a circuit where there is only one path from the source through all of the loads and back to

the source. This means that all of the current in the circuit must flow through all of the loads. Opening or

breaking a series circuit such as one bulb not working at any point in its path causes the entire circuit to

stop operating. So, the bulb A will not glow if the bulb B is not working.

19. An electric cell has two terminals; positive and negative. The metal cap is the positive terminal of the cell.

The metal disc is the negative terminal.

20. In connection A -the cell will be used up very rapidly. The chemicals in the electric cell get used up very

fast and the cell will no longer produce electric current. It will stop working.

21. Paheli will succeed by using aluminium foil strip in place of connecting wires as aluminium is a good

conductor, she has to connect one end of one aluminium foil with positive terminal of the cell and another

end with the negative of torch bulb and the other foil to be attached to the negative terminal of the cell and

the other end with positive of torch bulb.

(–ve)

(+ve)

4.5v bulb

filament

Zinc casing is thenegative electrode

The carbon rod with achrome cap on its end,is the positive elctrodes

emf = 1.5v

emf = 3.0v

emf = 4.5v

An Electric Circuit Drawn Using Symbols

Cell

Electric bulb

Swictch



1. To set up and electric current, we need a source of electricity like a cell or battery, conducting wires made

of copper or aluminum and a loop of wire to complete the circuit.

2. Circuit diagram.

3.

The metal parts of the torch must conduct electric current if the torch is to function, but they must also be

able to stand up to physical forces. The spring holding the cells in place should stay springy, while the

parts of the switch must make good electrical contact and be undamaged by repeated use.

The lamp and reflector make up an optical system, often intended to focus the light into a narrow beam.

The plastic casing is an electrical insulator. Its shape and colour are important in making the torch

attractive and easy to handle and use.

A different way of describing the torch is by using a circuit diagram in which the parts of the torch are

represented by symbols:

Lamp contact

Lamp filament

Reflector

Sealing ring(water resistant)

Plastic casing

Metal switch contacts

Slide switch

Metal spring C-size cells connected

in series

Structure of an electric torch

3V(2 C-size cells)

Lamp

Switch

Circuit diagram of an electric torch

There are two electric cells ('batteries'), a switch and a lamp (the torch bulb). The lines in the diagram

represent the metal conductors which connect the system together.

A circuit is a closed conducting path. In the torch, closing the switch completes the circuit and allows

current to flow. Torches sometimes fail when the metal parts of the switch do not make proper contact, or

when the lamp filament is 'blown'. In either case, the circuit is incomplete.

4. In an open circuit, the path of current is broken. So, the current cannot complete the circuit.

5. Electrical conductors carry, conduct off transmit electricity. For example, copper wires, or steel frames. or

metal flag poles.

Insulators do not conduct electricity. They block it. They prevent the transmission. Rubber. The plastic

around wires.

6. An electric cell is a device which converts chemical energy into electric energy. The cell has two different

metal plates — one is the positive terminal and the other is the negative terminal. These plates are kept

inside a chemical called electrolyte. One of the chemical is white in colour NH Cl (Ammonium chloride) 4

and other is a black powder MnO (manganese dioxide).2

7.

8. a. In A-No current will flow in B-current will flow from P to Q.

b. The bulb will glow only in case of B. It will not glow in case of A be cause the current shall not flow.

c. No brightness of the glowing bulb does not depend on the direction of current.

9. Activity Device

a. Picture TV

b. Cool Air Fan/airconditioner

c. Ice Refrigerator

d. Grinding Mixer

e. Heating Water Geyser

10.i. Bulb may have fused ii. The cell may be discharged iii. The cell may have been put inversely i.e. The

terminal +may have been connected instead of positive of cell to negative of contact point of torch.

Graphite rod

MnO2

Ammonium jellyZinc container


I. Give reasons.

J. HOTS questions

. The bulb will not glow since wood is an insulator and will not allow the current to flow.

2. The black tape is an insulating tape. The tape helps to seal the joints and prevent electric shock.

3. The three colours used in connecting wires are red, blue and green. Red corresponds to live wire (–),

blue corresponds to neutral (+) and green refers to the earth wire

. Satellites orbiting the Earth use solar power. Sunlight falling on large panels covered with thousands of

solar cells produce the electrical power needed by the systems. Solar panels will not "run down" like a

battery (completely renewable). Solar panels can be used together with a battery, which recharges when

the satellite is in the sun and provides the satellite's power. They are excellent for satellites studying the

sun or the planets orbiting close to the sun. They cannot be used easily for space exploration satellites

going deep into space because they will travel too far from the sun to receive sufficient power.

1. Silver, though is an excellent conductor, is a very expensive metal to be used as electric wires. So it is not

possible to use silver in wires.

2. Tap water is a good conductor of electricity. So, any leakage in the appliance will lead to an electric shock

if we handle it with wet hands.

3. Bare electric wires will lend electric shocks into the bodies of those who handle it. To prevent that a plastic

coating is provided as an insulator.

4. Electric switches enable us to make or break a circuit according to our needs. A circuit without a switch

will have continuous flow of circuit which means a lot of energy is wasted. It is also risky since it can lead

to overheating and circuit short current. So switches are very essential.

1

.

4


Chapter-12 : Understanding Magnets



1. can't 2. magnet 3. natural

4. pole 5. bar magnet 6. Heating,hammering

7. Alnico 8. North-south 9. CDs and DVDs

10. Like,opposite 11. airs 12. north-south

13. Chinese 14. needle 15. magnetosphere

16. Iron,cobalt

NCERT Questions

17. Bar magnets,cylindrical and horse-shoe

18. magnetic material 19. magnetic 20. bar magnet

21. two poles-north and south poles 22. two north and south poles

23. strong



NCERT Questions

7. False 8. False 9. True 10. False

11. True 12. True 13. False


1. Loadstone, iron, paper clip-magnetic, plastic scale, pencil, comb, steel scale and thread-non-magnetic.

NCERT Questions

2. a. iv b. v c. ii d. i e. iii

3. a. iv b. v c. ii d. i e. iii

4. a. iv b. iii c. i d. ii


E. Name them.

1. Magnet 2. Non-magnetic substances 3. Magnetic field

4. A suspended bar magnet 5. South pole



1. Magnets are substances that pull other metallic objects especially those made of iron, cobalt and nickel

towards it.

2. The area around a magnet in which the effect of the magnet can be experienced is called the magnetic

field.

3. The force with which the magnet pulls different substances towards itself is called magnetic force.

4. Magnetite is a rock containing iron ore. Its composition is Fe O .3 4

5. a. Magnet: A substances that pulls objects made of iron, cobalt and nickel towards itself is a magnet.

b. The area around a magnet in which the force of the magnet can be felt is called the magnetic field.

1. d 2. a 3. c 4. b 5. d 6. c 7. c 8. b 9. d 10. c

NCERT Questions

11. d 12. d 13. a 14. a 15. d



c. Magnetizing is the process of producing magnets out of an ordinary magnetic substance like iron.

6. The difference between a temporary and permanent magnet is that temporary magnets are created

using an electrical field. Once the current is switched off, it is no longer magnetic. A permanent magnet on

the other hand, such as the common ferro-ceramic magnet remains magnetic all the time because it was

manufactured with all of its iron particles facing the same way.

7. In a magnet, two like poles always repel. If we bring north pole of a magnet towards the north pole of

another magnet, they strongly repel. Opposite poles attract. The south pole of the magnet attracts the

north pole.

8. Self demagnetisation means loss of magnetic property in a magnet due to improper storage.

9. Electromagnets are used in :

(i) Electromagnetic cranes to separate magnetic scrap.

(ii) They are used in electric bells, transformers, motors and generators.

(iii) In Maglev trains which run on electromagnetism.

10. Magnets which are created in the laboratories are called artificial magnets. e.g., Made of aluminium,

nickel and cobalt – ALNICO- has magnetic property and so can be made into a magnet.

NCERT Questions

11. The blade of the pencil sharpener is made of iron. Iron is a magnetic in nature. That's why the sharpener

gets attracted by the poles of a magnet.

12. a. Each magnet has two poles i.e. North Pole(N) and South Pole(P).

b. Opposite poles of two magnets attract each other while like poles of two magnet repel each other.

c. A freely suspended magnet always aligns in N-S direction.

13. The two ends of the bar magnet represents the two poles-north and south.

14. Because steel has non-magnetic properties so it will not be attracted by magnet.

15. To test the tea dust mixed with iron flakes--- Spread a small quantity (2 tea-spoon) of the sample on a

piece of paper. Draw a magnet over it. Iron flakes, if present, cling to the magnet. The same test may be

carried out to trace iron flakes from tea half-dust and iron filings from tea dust.

16. a. We find that most of the iron filings are attracted towards the two ends of a bar magnet.

b. These regions are north and south poles of the bar magnet.


1. An electric bell and doors of refrigerators use magnets.

2. A freely suspended bar magnet aligns itself in the direction of earth's magnetic north-south direction.

3. Alnico is an alloy of aluminium, nickel and cobalt. It is used for making strong, permanent magnets.

4. Magnetite is the naturally occurring form of magnet, it was used as a primitive compass in ancient times.

It was made into the shape of a needle and floated on water to find directions.

5. Demagnetization occurs when the domains in the magnet de align themselves. In a magnet all the

domains are in the same direction. When they become haphazardly aligned, they get demagnetized.

This can happen on heating, hammering or dropping a magnet from a height.

6. Magnets should be stored in a dry place. It should be protected from heat. The free ends of a horse shoe

magnet should be in contact with an ordinary iron piece kept across so that the poles don't weaken. The

ends of a bar magnet should be in contact with the opposite poles of another magnet and the free end,

with an iron piece.

NCERT Questions

7. Hang up the magnet by a cotton thread so that it hangs freely. When it comes to rest, we notice that the

magnet is lying in a North - South direction. Magnetic compass works on the same principle. In past it

was used by sailors or travellers to find directions.


8. Take a rectangular piece of iron. Place it on the table. Now take a bar magnet and place one of its poles

near one edge of the bar of iron. Without lifting the bar magnet, move it along the length of the iron till your

reach the other and. Now lift the magnet and bring the pole C the same pole you began without to the

same point of the iron bar in the same direction as done before. Repeat the process for about 30-40

times. Your magnets is ready.

9. A compass needle always points toward the North-South direction. Once the needle become stable we

can conclude the East and West direction. In this way we can find directions with the helps of compass.

10. We can find the direction of magnet with the help of another magnet. Since like poles repel each other

and opposites attract we can easily find the direction of poles of the car magnet as the car will get

deflected by the same pole and will stick to the bar magnet if it faces the opposite pole of the magnet.

11. 1. We can use a magnet to find the magnet in these two iron bars, the iron bar will get attached to the bar

magnet and the magnet itself will attract or repel.

2. Or we can also use some iron fillings which would get attracted towards the magnet bar and the iron

bar will not attract any iron fillings.

12. a. The iron bar magnet (a) is a stronger magnet.

b. The (b) is not a magnet as it has not attracted any of the iron fillings.


1. Properties of magnets:

(i) A magnet attracts magnetic substances. Substances like iron, nickel and cobalt are magnetic and

they are attracted by a magnet.

(ii) Every magnet has two poles – the south and the north—no magnet exists with one pole. Even when

we break a magnet into many pieces, each piece as a north and South Pole.

(iii) Like poles repel and unlike poles attract. The North Pole always attracts the South Pole and south

pole attracts the north pole. But South Pole will repel another south pole and so also a north pole will

repel another north pole.

(iv) A freely suspended magnet will always align itself towards the earth's north – south direction how

much ever we try to disturb it.

2. Collect a lot of small iron nails or iron filings, leave them on a piece of paper and place a horseshoe

magnet over them. We will find that the pins cling to the magnet and maximum number of pins are found

near the poles. Repeat the same with bar magnets. Again you will find that maximum pins get attracted to

the poles. So we can understand that poles show maximum attraction in a magnet.

3. The magnetic compass is a small round box with a glass cover on it. A magnetized needle is set on a pin

in such a way that it can turn freely inside the box. The needle is made of steel. The compass has a dial

with eight different directions marked on it—north, south, east, west, northeast, northwest, southeast

and southwest. To find the direction the compass is placed on a horizontal surface and the needle is

allowed to come to rest. The dial is then rotated slowly until the needle alignment matches the printed

directions on the compass. Magnetic compasses are useful in finding directions especially in unknown

places. So mountaineers, mariners and in the cockpit of an aircraft, they are very useful. They are also

useful in mining and building orientation.

4. Electromagnets are those which gain magnetism while placed in a magnetic field. These are made by

winding a coil around an iron or a steel rod and passing current through it. The wire carrying current has a

magnetic field around it and a piece of iron placed in it gets magnetized. When the current flow is

stopped, the magnetism is lost by the iron. So, these are temporary magnets. Electromagnets are useful

in gadgets like electric bell, transformers, electric motors, electromagnetic cranes, etc.


5. Earth is considered a huge magnet. The magnetic property of the earth is due to the presence of

magnetic ore in the core of the earth. It is because of this that all magnets on the surface of the earth align

themselves towards north- south direction.

6. The poles of a magnet can be found with the help of another magnet whose poles are marked. Then the

two magnets are brought close together, mark the end which is attracted to the north of the second

magnet as south. The other end will be the North Pole.

NCERT Questions

7. The poles of a magnet can be found with the help of another magnet whose poles are marked. Then the

two magnets are brought close together, mark the end which is attracted to the north of the second

magnet as south. The other end will be the North Pole. The one bar magnet which is attracted by both the

poles is a magnet.

8. When a compass needle is brought near a bar magnet, the compass needle experiences a deflection.

This happens because of interaction of magnetic fields of the compass needle and the bar magnet.

9. Magnetise an iron needle using a bar magnet now, insert the magnetised needle through a small piece of

cork or foam. Let the cork float in water in a bowl or a tub. Make sure that the needle does not touch the

water. Your compass is now ready to work.

10. Magnetic poles always exists in pairs and never independent of each other. If a bar magnet is broken into

smaller pieces then each piece will again have two sets of poles. Like poles repel each other and unlike

poles attract each other. This property of a bar magnet can be used to distinguish a magnet and its

broken pieces.

11. A horse shoe magnet should be stored with a piece of iron across its poles. In case the poles are left free,

the magnets become weaker and are self demagnetised. Bar magnets should be stored with their unlike

poles together and the free hands safe inside a soft piece of iron.

I. Give reasons.

1. A freely suspended bar magnet always align itself in the north-south direction. The north pole of the

magnet aligns itself in the direction of the earth's North Pole and the South Pole aligns itself in the

direction of the earth's South Pole.

2. A magnet keeper is called an armature. It is a piece of iron or other object that acts as a keeper for a

magnet. The aim is to store the poles of the magnet in an attraction manner so as not to lose their

magnetic power.

3. A magnet should never be dropped because it could lose its magnetic property.

4. Not all magnetic materials conduct electricity, only the ones made from metals or metal alloys. Ceramic

magnets may or may not conduct, depending on their composition.

Lodestone is made of a mixture of various minerals, but the magnetic one is Fe O , which by itself is 3 4

magnetic but non-conducting.

5. All parts have same magnetic force as per gravity emanate from the central point. At a given distance

and without interference the magnetic field would be of same strength.

J. HOTS questions.

1. Magnetic force can spread in the magnetic field even through non-magnetic substances. For example,

keep some iron nails on a table. Pass a strong magnet back and forth below the table. You'll find the nails

move along the direction of the magnet showing that the magnetic force is reaching them.

2. If earth would lose its magnetic field, the solar winds, with the deadly stream of charged particles will

reach the earth and destroy it. The magnetic field of the earth protects the earth from solar winds.


3. If two magnets are placed side by side there will be mutual repulsion or attraction. This weakens the

strength of the magnet. To prevent this, bar magnets are placed side by side with opposite poles near. A

soft iron piece called a keeper is placed across the poles. This soft iron piece provides a path for the

magnetic field lines to form a continuous loop. Thus it helps in preserving the magnetic field.

4. A maglev train floats about 10mm above the guideway on a magnetic field. It is propelled by the

guideway itself rather than an onboard engine by changing magnetic fields. Once the train is pulled into

the next section, the magnetism switches so that the train is pulled on again. The Electro-magnets run

the length of the guideway. There are three components to work in a maglev train system:

A large electrical power source

Metal coils lining a guideway or track

Large guidance magnets attached to the underside of the train.

5. Here is the direction of current.

Now we can use the right hand thumb rule and fin the direction of magnetic filed. Take the direction of

thumb along the direction of current. The directions of the curled fingers give the direction of magnetic

field. Here the direction on magnetic field is a follows :

West East

West East

Going perpendicularly into the paper

Coming perpendicularly out of the paper

OBJECT TRANSPARENT /TRANSLUCENT/ OPAQUE

LUMINOUS /LUMINOUS

NON-

Air, Water Transparent Non-luminous

Piece of Rock Sheet of Aluminium, Mirror, Mooden Board, CD, Umbrella, Wall, Sheet If Carbon Paper, Sheet of Cardboard.

Opaque Non-luminous


Chapter-13 : Light, Shadows and Reflections



1. lunar eclipse 2. Photosynthesis 3. energy 4. luminous

5. a ray 6. artificial source 7. umbra 8. reflected

9. transparent, opaque, translucent 10. dark


1. True 2. False 3. False 4. True 5. False 6. False

C. Match the two column to make correct pairs.

a,c,f,--- Shadows, b,d,e,--- Image


1. a 2. b 3. b 4. c 5. b 6. c 7. a 8. a 9. c 10. a

NCERT Questions

11. c 12. d 13. d 14. b 15. c 16. c 17. c

E. Name them.

1. Luminous objects 2. Reflected ray 3. Lunar eclipse

4. Mirror 5. Translucent 6. Translucent



1. A torch and the sun are luminous.

2. Moon, mirrors are non-luminous.

3. Food, right temperature and oxygen are very essential for life on earth. Light energy is necessary for

food since photosynthesis can't take place without sunlight.

4. Stars are natural sources of light.

5. A log of wood is luminous when it burns.

6. The object can be called translucent.

7. Speed of light is 300,000 km/second.

8. An Italian scientist Galileo, attempted to measure the speed of light first.

9. Light can't travel through a bent tube. It always travels in straight line.

10. An image can't be formed on a screen.

11. The property of light to travel in a straight line is called rectilinear propagation of light.

12. The shadow is shortest when the sun is above the head – around Midday.

13. Red, green and blue

14. Transparent, opaque, translucent.

NCERT Questions

15. Opaque object make shadows.

16.


17. It will not be the same .The image formed by a small hole would be the sharpest image.

18. Transparent material.

19. A and B will form the shadow but C will not form the shadow.

20. The shadow will not be formed as it will be reflected back in case of screen A but there will be a shadow in

case of screen B.


1. Sun is millions of kilometers away from the earth. So, the light takes 8 minutes to travel from the sun to the

earth.

2. Objects which have their own light are called luminous. e.g., fuels, stars.

3. Objects found in nature that have their own light like stars, shooting stars, glow worms, radium, etc., are

natural sources of light.

4. The property of light to travel in a straight line is called rectilinear propagation.

5. A shadow is formed when an opaque object blocks the path of light. The area behind doesn't receive light

and so remains dark.

6. Rough surfaces scatter light rays and so the rays do not form a clear image. Images are formed when

reflected rays undergo regular reflection. When reflected rays scatter, many of them do not reflect

regularly. So, the image is not clear.

7. (i) Shadows are always in the direction opposite to light.

(ii) Shadows are always dark.

(iii) Shadows are always formed on a screen.

8. When the sun, moon and the earth come in a straight line, with the moon in between the sun and earth,

the shadow of the moon falls in some portions of the earth blocking the view of the sun from the earth,

leading to a solar eclipse. When the sun is completely blocked, it is total solar eclipse. When the sun is

partially blocked, it is partial solar eclipse.

9. The image of an object is seen in a plane mirror. When the object is placed in front of the mirror, the mirror

should be well polished and smooth.

10. A cylinder object can cast shadows in two ways. When the top circular view faces the sun, a circular

shape shadow is formed. When its horizontal side faces the sun, it casts a rectangular shadow.

11. To see the reflection, source of light is required. We can only see our reflection in the presence of light.

12. a. The colours of the image of the object will be the same as the colour of the object.

b. Transparent objects allow light to pass through them.

13. We can obtain more than one shadow of an object if light from more than one source falls on it. [For

example during a match being played in a stadium, multiple shadows of players are seen].

14. When the bird is flying very low close to the ground.

15. (i) By applying oil, grease, butter on it or pasting a butter paper on it.

(ii) Grinding (rubbing) the surface of the glass by any abrasive material.

NCERT Questions

Moon

A Sheet Of Polythene, Smoke, Fog, Sheet of Cellophone, Wire-mesh

A Piece of Red Hot Iron, Light Fluorescent Tube, Lighted Torch, Kerosene Stove, Sun Firefly

Translucent

Translucent

Translucent

NON-LUMINOUS

NON-LUMINOUS

NON-LUMINOUS

Flame Of Gas Burner


16. The Shadow a will be formed by torch A and shadow b will be formed by B.

17. No, it will not change.

18. The colour of shadows of all three towels will be the same.

19. The colours of the image of the shirts will be the same as the colour of the shirt.

20. The shape formed will be of a flower and the colour of the shadow will be black.

H.Long answer questions.

1. Natural sources of light are those which glow in nature –e.g., stars, glow worms, fireflies, etc. Artificial

sources of light are those which have been created by man, e.g., electric bulb, candle, petrol, etc.

2. A narrow path taken by light represented by a straight line with an arrowhead is called a ray of light. A

beam of light is broader and is a collection of several rays.

3. Light travels in a straight line. Take a tube of about 35cm. You can take an empty agarbatti container.

Keep sure that it is open from both the sides. Keep a lighted candle on a table and try to view it through the

tube. Then bend the tube a little so that it is not absolutely straight. View the candle flame again .You will

not see the flame. It is because the light travels in a straight line and can't take a bent path.

4. (i) Shadows are formed when light is blocked by an opaque object.

(ii) The area where light does not reach is called the shadow.

(iii) Shadows are always dark or grey.

(iv) The size and shape of the shadow depends on the distance between the light and the object.

5.

6. Solar eclipse is always on a new moon day. On this day the moon comes between the sun and earth in a

straight line. When the moon is in that position, its dark side faces the earth since moon becomes visible

only when it reflects the sun's light. Eclipse occurs on a new moon day, because by being in between the

sun and earth, it blocks some of the light coming from the sun and its shadow falls on earth.

7. A shadow is a region of absence of light. An image is due to the presence of reflected rays meeting at a

point.

8.

9. Food production on earth is possible due to photosynthesis which can't take place without light. Fuels are

obtained from buried plants and animal remains which have transformed into coal, petroleum, etc.,

because of heat which has been received from the sun. So we are directly or indirectly dependent on

sunlight for food and fuel.

incidentparallelrays

reflectedparallelrays

incidentparallelrays

scatteredreflectedrays

tiltednomals


10. Transparent objects allow the light to pass through them completely. They are like water, clear glass,

clear cellophane sheet, etc.

Translucent objects allow only a part of the light falling on them to pass through. So the visibility through a

translucent object is hazy. Frosted glass, coloured water, pure marble, gem stones, butter paper, etc.,

are translucent.

Opaque objects are those which do not allow light to pass through. They block the path of light. e.g., a

stone, brick wall, wood, pieces of metal, etc., are examples of opaque objects.

NCERT Questions

11. We can see the shadow of football lying on the ground because the ground acts as a screen for it.

However, when the football is kicked high, the ground, which is acting as a screen is away from the

football, hence no shadow of the football will be formed on the ground.

12. Possible reasons (i) The screen away from the ball. (ii) The beam of light from the torch is falling

parallel to the screen on the ball. (iii) The torch is kept away from the ball.

13. In the case of plywood the shadow will be in the shape of a rectangle. This is because the plywood is

opaque. In case of muslin cloth the shadow formed will be somewhat hazy and in the shape of muslin

cloth. This is because muslin cloth is translucent. In case of transparent glass no shadow will be formed.

I. Give reasons.

1. Your shadow is the result of your body intercepting light on its way to a target. You can see your shadow

because there is still some light moon light or street light. If it was pitch dark you will not be able to see

your shadow.

2. Plants prepare their food in the presence of sunlight. Photosynthesis uses the light energy obtained from

the sun. Light is the most important form of energy essential for life on the earth. When we burn wood or

coal to cook food or to warm ourselves, we actually use the light energy stored in them since many years.

Therefore we depend on light energy for food warmth and fuel.

3. A shadow is formed in a region where there is no light shining on it. It is distinctive to the human eye

because the area surrounding the shadow has light and there will thus be a contrast. A shadow is not a

tangible thing, neither is it an illusion, because it is not formed by light rays but rather, the absence of it.

On the other hand, an image, say one that is formed when you look into a mirror, or when light passes

through some lens, is caused by light rays. An image can be real or virtual. Real images can be captured

on a screen, while virtual images cannot be caught on a screen.

J. HOTS questions.

1. To see any object or image, we need light. The reflected rays of light falling on any object enable us to see

it. In the absence of light, in a dark room, therefore we cannot see anything.

2. Shadows are regions of absence of light. Where there is no light, there will be darkness or black region.

3. The sun is somewhat spherical and because of the distance between the sun and the earth and the

brilliance of sun's light, we only see the disc of the sun and cannot observe the details. The image we get

in a photograph or screen will be upside down but it can't be differentiated from an upright image.

4. A shadow is formed when an opaque object blocks the path of light because light travels in straight lines.

Light cannot bend around the object so it forms a shadow. The shadow with translucent objects is not a

solid 'black' colour. It can be the same colour as the object and the shadow allows you to see through it

more than an opaque objects shadow. A shadow formed by an opaque object is much darker than formed

by a translucent object.

5. Shadow formation depends on how many different light sources there are that illuminate the object in

question. One shadow per light source. Even if you can't see the shadow because it is drowned out by the

other light sources, the shadow still gets cast.

6. A pinhole camera forms an image. Light reflects in all direction from each point of the object to form

Inverted (upside-down) image as there is no refracting or reflecting optical element to change the path of

the rays of light.


Chapter-14 : Water



1. soil erosion 2. Cholera, typhoid 3. Water cycle 4. hail

5. surface water 6. ground water 7. conservation 8. rain water harvesting

NCERT Questions

9. evaporation 10. condensation 11. drought 12. floods


1. True 2. True 3. False 4. False 5. True 6. True

7. True 8. False

NCERT Questions

9. False 10. False 11. True 12. False 13. True

C. Match the facts given in column I to images or shadows as given in column II.

1. Condensation--- a, c 2. Evaporation--- b, d, e


1. a 2. a 3. b 4. c 5. a 6. b 7. c

NCERT Questions

8. d 9. d 10. b 11. d 12. c 13. d 14. a 15. c 16. d 17. c

E. Name them.

1. Luminous objects 2. Reflected ray 3. Lunar eclipse

4. Mirror 5. Translucent 6. Translucent



1. Our body fluids dissolve all the waste generated in different organs, and pass it on to the kidneys from

where they are excreted as urine. Urine has a lot of waste products in soluble form.

2. Plants need water for:

(i) germination and growth (ii) photosynthesis

3. Rivers and springs are sources of fresh water.

4. Even though 3/4th of earth is covered with water, only 3% is available as fresh water for use.

5. Water that percolates into the soil and accumulates in the lower layers of rocks under the soil is referred

to as water table.

6. Water which is fit for human consumption is called potable water.

7. Plants need water for photosynthesis.

8. Water evaporates faster at a higher temperature.

9. Cholera and typhoid spread during floods.

10. Water changes to water vapour during evaporation.

11. Sea water has high salt concentration and is not fit for drinking.

12. Floods can be controlled by planting more trees and building dams for storing excess water.

13. Rivers and ponds are fresh water sources.

14. Conserving water can be done through rain water harvesting.

15. Three-fourths of the earth is covered with water.

16. Transpiration is the process by which plants lose water.


1. Condensation is a process of conversion of water vapours to water.

2. Evaporation is the process of conversion of water into water vapours from the surface of the earth, due to heat. It is a continuous process taking place at all temperatures.


Transpiration is the loss of water from the leaves of plants. It happens due to osmotic pressure.

3. Wet clothes dry fast under direct sunlight since the rate of evaporation is higher at higher temperature.

4. Animals need water for drinking, washing, bathing and for all biological activities. Inside the body, the nutrients are carried because of water in blood and other body fluids and waste is excreted through urine and sweat. It helps to regulate body temperature too.

5. Water can exist as solid in the form of ice, as liquid in the form of water and as gas in the form of water vapours.

6. Take a glass and fill it with ice cold water. After a few seconds examine the outer surface of the glass. It will have tiny drops of water which have come from the surrounding air. The air has water vapours which condense, on touching the cold surface and hence the drops are formed.

7. Collecting rain water which falls on roof top of buildings as well as those draining into the ground in specially built storage tanks with filter beds and utilizing the water of watering plants and toilets, etc., is known as rain water harvesting. The collected rain water can also be discharged into the ground to recharge ground water.

8. The water drops on the wind screen of the car is as a result of condensation of atmospheric water vapour at low temperatures.

NCERT Questions

9. The cool surface of cooled bottle cools the air around it, and the water vapour of the air condenses on the surface of the bottle.

10. The moist air coming out from mouth condenses on glasses to make glasses wet.

11. The process of condensation plays an important role information of cloud. As water vapour goes higher from the surface of the earth, it gets cooler. When the air moves up it gets cooler and cooler. At sufficient heights the air becomes so cool that the vapour present in it condenses to from drops of water called droplets. It is these tiny droplets that remain floating in air and appear to us as cloud.

12. It does not rain for on two or year, The soil continues to lose water by evaporation and transpiration. Since it is not being brought back by rain, The soil becomes dry. The level of water in ponds and wells of the region goes down and some of them may even dry up. The ground water may also become scarce. This may lead to drought.


1. Water from the oceans, rivers, seas and lakes changes into vapours as it evaporates due to the heat of the sun. The water vapours that rise up into the atmosphere and as the temperature falls at higher altitudes, condensation of water vapours take place forming clouds, when the clouds become heavy; they fall as rain or snow. This continuous process of evaporation of surface water followed by its condensation is called water cycle.

2. For conservation of water first and foremost, the available water should not be wasted.

(i) Avoid wastage of water by ensuring that taps don't leak, tanks don't overflow and use buckets and mugs to bathe rather than showers. The water that we use for washing rice or vegetables, etc., can be used for watering plants.

(ii) Adopt measures like rain water harvesting and grey water recycling for reuse of water in areas where it is possible.

(iii) Make sure that taps are tightly closed when we go on a holiday.

(iv) Plant trees wherever possible to help in water percolation.

3. As evaporation takes place from the surface of the earth, water droplets condense at the higher reaches and form clouds. It happens due to low temperature prevailing there. As more and more vapours condense, the clouds get bigger and bigger.

4. Water can be the cause of disasters like floods and drought. Floods are caused due to excess of rainfall letting water level in rivers, lakes and ponds rise above the banks. Agriculture fields, forests, villages and cities may be submerged in water. This can result in extensive damage to crops, animals, property and human life. Floods disrupt life and also lead to outbreak of deadly water borne diseases like cholera, typhoid, jaundice, etc. Drought are caused when water becomes acutely short. Droughts cause crops to dry up and it becomes difficult to get food and fodder leading to death of man and livestock. The coastal


areas face the double danger of tsunami and cyclones. A tsunami is caused by a strong underwater earthquake leading to gigantic waves hitting the coastal floor. A cyclone is a very strong wind accompanying heavy rains that cause huge waves called tidal waves and cause flooding.

5. Sometimes monsoons fail and there is acute shortage of water. The soil becomes dry and the land looks parched. The level of water in ponds and wells of the region gradually reduces and some of them may even dry up. This is a condition called drought. The crops dry up and food and fodder are destroyed leading to death of animals, livestock and human beings.

I. Give reasons.

1. Drought is a disaster because it occurs when it does not rain for one or two year, the soil continues to lose water by evaporation and transpiration. Since it is not being brought back by rain, the soil becomes dry. The level of water in ponds and wells of the region goes down and some of them may even dry up. The ground water may also become scarce. This may lead to drought it becomes difficult to get food and fodder.

2. We can not use sea and ocean water for irrigation and drinking because sea and ocean water is highly saline. It contains about 10,000-35,000 ppm of dissolved salts.

3. The human body mainly cools down through vaso-dilation and sweating. Vasodilation occurs when the blood vessels appear close to the skin surface enough for the blood to loose some of its heat. Sweating is the most common way that the body uses to cool down and internal body heat is lost through evaporation of sweat on the skin surface.

4. Environmental factors that affect the rate of transpiration.

1. Temperature: A high temperature increases the rate of evaporation of water from the mesophyll cells. So when the temperature is high the rate of transpiration will be high. A high temperature also increases the capacity of the atmosphere for water vapour.

2. Humidity: A high humidity will lead to a low transpiration rate because the surrounding of the plant will already be circulated with water vapour.

3. Wind: When there is wind, the rate of transpiration is high because wind blows away water vapour from around the leaves creating more room for evaporation. When there is still air then the surroundings of the leaf will be saturated with water

4. Light Intensity: Light affects stomatal opening and closing called stomatal aperture.

5. Atmospheric Pressure: When the pressure is low, the rate of transpiration is high.

5. Water is important to the human body because your body needs to be constantly hydrated. In addition, more than two thirds of the body is made up of water. About 95% of your brain and 90% of the lungs are made up of water.

J. HOTS Questions.

1. Both drought and flood result in increase in food prices because demand is much more than the supply. Loss of food crops due to floods and drought also makes it necessary to import grains from other countries which push up the food prices.

2. Dehydration in summer is due to high atmospheric temperature which increases the rate of evaporation even from our bodies. To maintain the body temperature constant, we sweat and so sweating is very profuse when temperatures is high. To compensate for the loss through sweat, we need to drink a lot of water. In case of severe losses due to vomiting or diarrhoea, oral rehydration should be done to prevent dehydration.

3. If water is not recycled by nature than there will be deficiency or scarcity of potable water, rise of level in the oceans, coastal and low lying areas will be submerged in water. We would run out of water and everything would die. It would earth's desertification.

4. The major part of river water, rain water and water we use seeps down through the soil and form Layer of ground water called Layer of water table. This water will not be able to seep down the layers if we concretize the upper layer only causing a major shortage of underground water.


Chapter-15 : Air Around us



1. space, pressure 2. air/gas is present in water 3. dampness

4. increasing pressure

NCERT Questions

5. atmosphere 6. carbon-dioxide


1. True 2. True 3. False 4. True 5. True 6. True

NCERT Questions

7. True 8. True 9. False 10. False


1. a. iv b. iv c. i d. iii e. ii

2. a. iv b. iii c. v d. i e. ii


1. a 2. b 3. c 4. d 5. c 6. b

NCERT Questions

7. b 8. c 9. d 10. b 11. a 12. a 13. a 14. c

E. Name them.

1. Wind 2. Carbon dioxide 3. Atmosphere

4. Nitrogen 5. Water vapourt



1. The amount of water vapour present in air is known as humidity.

2. Plants release oxygen during photosynthesis.

3. Nitrogen is required for plant growth.

4. Ultraviolet rays are harmful rays.

5. The layer of air around the earth is atmosphere.

6. Nitrogen forms the major components of air.

7. Ozone prevents ultraviolet rays from reaching the earth's surface.

8. Fish breathe the air dissolved in oxygen through gills.

NCERT Questions

9. Air contains some gases in air are mainly nitrogen, oxygen, small amounts of carbon dioxide, and many

other gases. Air contains mostly nitrogen and oxygen. These two gases together make up 99% of the air.

The remaining 1% is constituted by carbon dioxide and a few other gases, water vapour and dust

particles.


1. Fish breathe through gills.

2. (i) Oxygen is very essential for respiration in all living beings.

(ii) Without oxygen no burning takes place.

3. The bacteria (nitrogen fixing bacteria) living in the root nodules of leguminous plants convert the

atmospheric nitrogen into the form usable by green plants. Some amount of nitrogen is also fixed by

lightning.


4. 1. Photosynthesis stores energy in organic compounds. Respiration used organic compound to free

energy for cellular use.

2. Photosynthesis occurs in 2 phases the light and dark reactions. Respiration in three phases

glycolysis, Krebs and the ETS.

5. Ozone layer on the atmosphere filters the harmful ultraviolet radiations of the sun and protects all forms

of life on earth.

6. Heat some water in a saucepan and watch. Even before the water begins to boil, tiny bubbles form at the

base of the saucepan. This proves the presence of air in water.

7. Organisms living in the soil breathe through the tiny pores on the skin, talking up the oxygen trapped in

the gaps of the soil.

8. 1. Winnowing. 2. Formation of clouds. 3. Respiration.

4. Photosynthesis. 5. Transpiration.

9. Harmonium, flute, trumpet, violin, guitar, xylophone, bass, drum.

10. a---WINDMILL, b---OXYGEN, c---SMOKE, d---DUST

11. a---Oxygen and nitrogen together make up 99% of air.

b---Aquatic animals use dissolved air in water for respiration.

c---Moving air is called wind.

12. a---wind, b---mixture, c---direction, d---cylinders

13. a---a mask is covering the face and nose of the traffic policeman, b--- vehicles produce smoke, which is

bad for health therefore to avoid breathing dust partials by covering face.

14. This is because air dissolved in water starts escaping in the form of tiny bubbles due to heat from the sun.


1. Uses of air:

(i) Air is very important for survival of life since it provides oxygen for breathing and CO for 2

photosynthesis.

(ii) Wind contains energy. Windmills rotate and generate electricity and draw water from the tube wells

and to run flour mills.

(iii) Air helps in movements of gliders, parachutes, airplanes and sailing yachts.

(iv) Air helps in seed dispersal.

(v) Presence of air helps in the flight of birds, bats and insects.

2. The atmosphere contains carbon dioxide which absorbs the heat radiations coming from the sun. This

heat is trapped in the atmosphere keeping the earth warm. Due to this the temperature of the earth is

warm enough to sustain life and also warm enough to keep the water in liquid form.

3. Oxygen is essential for burning. We can prove it by the following activity:

Take a shallow container and fill it with water. Fix a small candle in the centre of the shallow container.

Light the candle and then cover it with an inverted glass. Observe carefully what happens to the burning

candle you'll notice that the candle stops burning since it uses up the oxygen present inside the inverted

glass. Once the oxygen is used up the candle can't burn.

4. Plants utilize CO and give out oxygen. The oxygen of air is used up for breathing by all plants and 2

animals and they give out CO . So, there is a cyclic process of oxygen getting converted to CO and CO 2 2 2

getting converted to oxygen again. So, plants and animals are actually helping each other.

NCERT Questions

5. Two lighted candles are taken. one candle is covered a fixed in a tumbler containing water. This candle is

covered by an inverted glass. After sometime, the covered candle gets extinguished and water rises

upto 1/5th is oxygen. The candle extinguished as soon as all the oxygen was usedup. Explanation:


Burning candle goes offafter sometime

when covered with air tight jar

During burning, oxygen is consumed and carbon-dioxide is released. After sometime no oxygen is left

inside the jar and flame goes out. Once the candle goes off, the temperature surrounding the candle

cools down and volume of air (carbon dioxide) decreases. Thus water rises up little in the jar.

6. There is the interdependence of plants and animals. Both plants and animals respire i.e. they inhale oxygen

and gives out carbon dioxide in the atmosphere. Plants take carbon dioxide from the atmosphere and

prepare food. This is called photosynthesis. During this process, plants give out oxygen to the atmosphere.

Therefore plants and animals help each other in the exchange of gases in the atmosphere.

7. (a) A firki does not rotate in a closed area due to lack of air movement.

(b) The arrow of weather cock points towards a particular direction at a particular moment because of

the direction of the movement of wind.

(c) This is because everything is filled with air.

(d) This is because fine hair and mucus present inside the nose prevent dust particles from getting into

the respiratory system but this does not happen when we breathe through mouth.

8. a. Oxygen----The balance between oxygen and carbon-dioxide is disturbed. All living beings will die-

plants as well as animals.

b. Nitrogen---- If it were to suddenly disappear tomorrow then we would be left with a low pressure

almost pure oxygen atmosphere, a highly dangerous situation with unstoppable fires commonplace,

humans could still breath however.

c. The level of carbon dioxide in your blood is what triggers your lungs to breathe, oxygen has nothing

to do with it. If the CO level in your blood gets too low, your brain will tell your lungs to stop breathing. 2

Divers have died because they blew out too much CO , and their oxygen level dropped too low 2

before their brain told them that they needed to breath, so they passed out underwater and drown.

Plants would die without carbon dioxide, therefore we would all die because there would be nothing

to produce oxygen.

9. a. When a tumbler containing water heated, tiny bubbles appear on the inner side. These bubbles appear

before the water starts boiling. So, these must be air bubbles. This shows that water contains air.

b. Yes, they will appear because on heating the gas dissolved in water starts escaping.

10. Roadside plants are dull looking due to the heavy vehicular and lead pollution on the road.

I. Give reasons.

1. A lump of cotton wool shrinks in water because the air inside wool cotton is driven out by water. The

layers stick together and hence the lump shrinks.

2. Pressure due to the fluids moving inside our body (such as blood ,the air in our lungs etc.) balances the

atmospheric pressure and thus we don't feel it.

When people living in plain areas go to hilly areas(at much higher heights), they sometimes experience

bleeding from nose and ringing in ears... this is because at higher altitudes the atmospheric pressure is

lower but pressure due to blood remains same and thus blood oozes out of the weak capillaries of nose.

Also under water large pressure is felt since there the value of our body pressure is less than the outside

pressure.

3. Air is important as it provides oxygen and other gases that are essential for the survival of human beings

and plants. Humans breathe in oxygen from the air in order to live as it facilitates many processes in the

body while plants require carbon dioxide in order to manufacture food in the process of photosynthesis.

J. HOTS questions.

1. Wool will act as an insulator preventing oxygen from reaching the fire. This is helpful in putting out fire

since burning can't take place without oxygen.

2. Lotus has stomata on the upper surface because its lower surface is submerged in water and so

exchange of gases can't take place easily . It is an adaptation in aquatic plants to survive in water.

3. A person cannot sleep under the tree during night because trees release only carbon dioxide at night and

humans need oxygen to breathe. Due to lack of oxygen there would be a lot of suffocation which would

not allow person to breathe properly. Thus, one cannot sleep under the tree at night.

4. Breathing problems occurs in summer months when pollens, dust particles and spores are present in

large number. People allergic to these particles develop breathing problems.



Chapter-16 : Waste Management



1. organic 2. red worms

3. fruits, vegetables, not milk, and meat 4. reduce, reuse, recycle

5. green, biodegradable, blue, non-biodegradable



7. True 8. True


1. a. ii b. v c. iv d. i e. iii


1. c 2. b 3. c

NCERT Questions

4. b 5. a 6. b 7. a 8. d 9. a

E. Name them.

1. Garbage 2. Biodegradable waste 3. Recycling

4. Landfill 5. Vermicomposting



1. The three Rs stand for Reduce, Reuse and Recycle.

2. Recycling is a process of collecting discarded unusable materials and converting them into usable and

useful products.

3. Composting is a process in which the biodegradable waste is converted into manure by burying them

underground and letting the decomposition take place.

4. Waste disposal from hospitals, poultry farms and abattoirs should be specially taken care of since a lot of

infection can spread from there.

5. Landfills are areas where the biodegradable wastes collected from cities are dumped. These are low

lying areas outside the city limits where the waste is used to raise the ground level. Over a period of time,

the landfills get completely covered and are converted into parks.

6. E–waste refers to broken electronic items. The waste parts of computers, satellites, television parts, etc.,

comprise the e–waste. They contain harmful metallic components which should be carefully disposed off.

NCERT Questions

7. Column III

a. earthworm

b. Dig pit and fill with garbage

c. paper bags

8. i. Compost: Substances converted into manure for use in garden.

ii. Landfill: Garbage buried in pits in an the area.

iii. Recycling: Reuse of used material in the useful form.

9. a. reuse, b. garbage, c. vermicomposting, d. landfill


1. Waste segregation means separation of biodegradable from non-biodegradable and further

segregating them as hazardous and non-hazardous for efficient and safe disposal.

2. Composting is done by burying the biodegradable wastes in compost pits where they are allowed to be

acted upon by soil organisms. It takes 2-3 months to get the manure out of compost pits.

Vermicomposting is done by introducing red worms to speed up the process of decomposition. The

method gives us manure in a month's time.


3. Metal cans are collected and taken to recycle centers where they are shredded and cleaned. The shreds are then melted in a furnace and rolled into new sheets. These sheets are ready to be used again.

4. The 3 Rs is the motto—used for conserving our environment and resources. The 3 Rs refer to Reduce – reduce wastage; Reuse – Reuse materials as many times as one can; and Recycle – Recycle materials to get fresh usable form of it so that they are put to use once again.Reducing wastage of our resources like paper, metals, cloth, etc., can be done if we are judicious in their use. Huge amount of paper wastage has led to deforestation on a large scale. Certain measures we can adopt are to use both the sides of paper to write on, use less of paper napkins and toilet rolls, etc.Reuse: A lot of things we don't require can be very useful for someone else. So reusing can help to distribute materials to the needy and save much of our resources. For eg: Old clothes which don't fit us any more can be passed on to destitute homes, to the poor and needy people. Old books can be sent to libraries and organizations which are helping the poor.Recycle: Recycling, of course, is done by converting the unusable form into usable form. Metals are melted and reused. Paper can be turned into pulp and reused as paper once again. Many types of plastics can be melted and reset.

5. Waste production can be reduced if we:(i) Use cloth bags instead of depending on plastic bags while Shopping(ii) Ensure that whatever we buy are in recyclable packing.

NCERT Questions6. Non bio-degradable waste like pieces of cloth, polythene bags, broken glass, aluminium wrappers,

nails, old shoes and broken toys cannot be converted into compost by the redworms.7. i. composting, ii. vermicomposting, iii. recycling8. a. Burning of leaves and other plant wastes produces smoke and gases that are harmful to our health.

They may lead to asthma and lung diseases. b. Instead of burning, these plant wastes must be converted into manure.

H. Long answer questions.1. Waste generated in hospitals are of many types and can be of serious health consequences. There are

different coloured bags or bins which are recommended for different kinds of hospital wastes: Yellow bags: are meant for wastes which contain body fluids like blood, pus, etc., and bandage, guage, cotton and so on. Red bags: are for catheters, injection syringes, tubing, IV bottles, etc., which are plastic wastes.Blue bags: are for collecting glass bottles, broken glass articles and discarded medicines.Black bags: are for sharp metallic items like needles, blades, cutters ,etc.

2. Waste segregation at home should be done with conscious effort. Biodegradable wastes should be collected separately in a bin (green colour). Non-biodegradable wastes which can be recycled should be collected in a separate bin (blue coloured) and all e–waste, cells, batteries, CFL bulbs, paints, etc., should be collected separately and disposed off appropriately.

3. Vermicomposting is a modern technique in which red worms are used for speeding up the decomposition process. The worms are introduced into the compost pits and are fed fruits, vegetables, bread, leaves and coffee grounds. Foods like milk, oil, meat, faecal matter of dogs, cats, etc., should be avoided. The compost is ready in a month's time and the number of red worms also doubles within this period. Vemicomposting is being widely used by farmers to produce chemical free organic fertilizer.

4. Recycling Paper: Since paper is a product of plants, a huge number of trees is cut in order to meet the never ending demand for paper so to save trees, recycling of paper is a very important step. The used and discarded paper items are purchased by scrap dealers and are sent to factories where the paper is shredded, mixed with water, and made into a pulp. The ink is removed from it and then the pulp is passed through large rollers to squeeze out water and flatten it into big sheets which are used again. Glass: The waste glass items are collected and carried to recycle factories. They are sorted out according to the colour and then melted in a furnace at very high temperature. The molten glass is remoulded and used.Fabrics: Old, discarded fabrics which are collected are sorted out. The clothes in good condition are donated to the needy. The ones which can't be reused are sorted out according to the type of fabric and colour of fabrics. The fabrics are shredded and spun into fibres. The fibres are then spun into fabrics once again.


5. Advantages of the three Rs:

(i) Recycling helps to save our resources especially the non-renewable resources.

(ii) Recycling saves trees. Paper is a product of trees. The higher the amount of paper we use, the

higher is the number of trees cut.

(iii) Reusing materials and reducing wastage helps us to save energy to a large extent since the fossil fuels

we might expand in manufacture of fresh items will put a higher demand on our energy resources.

(iv) This, in turn, reduces greenhouse gas emissions and reduces the use of non-renewable raw

materials like metals.

(v) Finally, we can avoid the major problem we face of garbage and trash disposal. It is becoming more

and more difficult to find landfill sites for safe trash disposal.

6. Waste production can be reduced in the following ways:

(i) Usage of eco friendly packing materials is preferable to plastics which are not eco-friendly.

(ii) We should carry our own shopping bags whenever we go shopping so that we avoid taking carry bags.

(iii) Bulk purchases wherever possible can reduce the quantity of packing materials.

(iv) Look for brands which have recyclable packaging.

(v) Carrying our own water bottles and home-prepared snacks while going out will save a lot of polypet

bottles and food containers.

(vi) Usage of rechargeable batteries in place of disposables will reduce hazardous waste.

(vii) Dispose off electronic items in places where they are carefully handled.

(viii) Save and reuse all gift wrappings and gift bags, envelopes one side blank papers, etc.

(ix) Options are available to carry out most of our transactions on-line, like e-banking, e-ticketing, e-bills

and e-bank statements which will reduce paper usage.

NCERT Questions

7. (a) Garbage Disposal is the responsibility of every citizen. If we continue to generate so much garbage,

very soon our beautiful earth will convert into a big garbage-bin. Non-biodegradable waste like

plastic is harmful to our environment as well as to our health. We must ensure ways to reduce

production of garbage. Wherever possible, we must use recyclable material in our daily use.

(b) Yes, it is possible to reduce the problems relating to disposal of garbage to a large extent. We should

use those materials which are recyclable. We should avoid or reduce the use of non-biodegradable

materials at minimum level. While throwing out garbage in trash can, we should separate

biodegradable waste from non-biodegradable and throw them in separate bins.

8. No doubt compost is better to use than chemical fertilizers due to following reasons:

1. Compost is much easier to prepare Compost is environment friendly whereas fertilizers can harm

our health and the environment.

2. Compost does not pollute our environment.

3. Compost decomposes bio-degradable waste into natural soil. It conserves our environment.

9. Garbage Items Make manure or not

a. Egg shells ü

b. Straw ü

c. Dry flowers ü

d. Pebbles û

e. Broken pieces of glass û

f. Nails and screws û

g. Plastic bangles û

h. Left over food ü

i. Steel broken vessel û

j. Dead animals ü


10. Family X is environmentally conscious as they are segregating their garbage.

11. Step-1---F Step-2---C Step-3---E Step-4---A

Step-5---D Step-6---B

12. a. A ragpicker---He is the one picks up all recyclables. He is the one who reuse and recycle by reducing our waste going directly into the landfill site. These people survive on our mistakes of not segregating our waste.

b. When I see a cow eating a polythene I think that it is due to our negligence and selfish interest that is putting even the innocent animals into danger. This is the result of not using a biodegradable cloth bag. This is the result of commercialisation.

c. We actually blame the government for not doing anything for this but the real problem lies with people who do not segregate their garbage, the heap will never be there had we been segregating it.

13. The paper is cut or torn into strips, and soaked in the paste until saturated. The saturated pieces are then placed onto the surface and allowed to dry slowly. The strips may be placed on an armature, or skeleton, often of wire mesh over a structural frame, or they can be placed on an object to create a cast. Oil or grease can be used as a release agent if needed. Once dried, the resulting material can be cut, sanded and/or painted, and waterproofed by painting with a suitable water-repelling paint Before painting any product of papier-mâché, the glue must be fully dried, otherwise mould will form and the product will rot from the inside out.

14. A plastic ban is imposed but it is difficult to imagine our life without plastics-toys, shoes, bags, pens, combs, toothbrushes—the list is long. Even parts of refrigerator, AC, radio, television etc. The problem arises when we use plastics excessively and are ignorant about ways of disposing their waste. We act irresponsibly knowing well about its harmful effects. All plastics give out harmful gases upon heating or burning. These gases may cause many health problems including cancer in humans. The government has laid down guidelines for recycling of plastics. We should minimise the use of plastic bags and then throw it away.

15. Plastic bags should not be burnt as they emit poisonous gases in the atmosphere and can be hazardous for health.

16. a. Putting cooking medium in the dram blocks it. b. It will clog the drain.

c. Drain is for flowing dirty water as a very narrow passage so the items like tea leaves, cotton swabs and old soft toys would clog or block the drain.

17.a. A paper bag is biodegradable. b. All of them should do this.

c. Earthworms.

I. Give reasons.

1. Household waste should be separated daily into different bags for the different categories of waste such as wet and dry waste, which should be disposed of separately. One should also keep a bin for toxic wastes such as medicines, batteries, dried paint, old bulbs, and dried shoe polish. Wet waste, which consists of leftover foodstuff, vegetable peels, etc., should be put in a compost pit and the compost could be used as manure in the garden. Dry waste consisting of cans, aluminium foils, plastics, metal, glass, and paper could be recycled. If we do not dispose of the waste in a more systematic manner, more than 1400 sq. km of land, which is the size of the city of Delhi, would be required in the country by the year 2047 to dispose of it.

2. Oil clogs the drains so should not be drained into the drain.

3. Red worms should not be fed with salt, pickle, oil, vinegar and milk preparations as food. If we put these things in the pit, diseases causing small organisms start growing in the pit.

J. HOTS questions.

1. Recycled paper helps us to save a lot of trees which otherwise would have been cut down for manufacturing paper. Trees are very essential for purifying air, to maintain the ecological balance, to help cloud formation, etc.

2. The e-wastes which have hazardous materials are brought to developing countries and small children are engaged in dismantling them. People who are employed in such places are also not given any protection from exposure to harmfull materials. This places them in the risk of facing dangerous consequences.

Date post:	27-Mar-2018
Category:	Documents
Upload:	vannhi
View:	215 times
Download:	2 times

JJJJ iiii wwww aaaa nnnn CCE - Jiwan Books Book-6 Final.pdfCarnivores have long sharp teeth for...

Documents