The City School University Road Campus Science Question Bank Class : 8 Chapter 1 Food and Digestion 1. Maximum carbohydrates are obtained from a)nuts b) whole grain food c)fatty fish 2. Vitamins, minerals and proteins in suitable amounts are given to body by a)whole grain food b) fatty fish c) nuts 3. Sources of proteins includes a)Fish b)poultry c)all of them 4.A diet containing right amount of energy, carbohydrates, proteins, fats, fiber, vitamins, minerals and water to fulfill requirement of body is called a)nutrition b)balanced diet c)perfect diet 1
Transcript
The City SchoolUniversity Road Campus Science Question Bank
Class : 8
Chapter 1 Food and Digestion
1. Maximum carbohydrates are obtained from
a)nuts
b) whole grain food
c)fatty fish
2. Vitamins, minerals and proteins in suitable amounts are given to body by
a)whole grain food
b) fatty fish
c) nuts
3. Sources of proteins includes
a)Fish
b)poultry
c)all of them
4.A diet containing right amount of energy, carbohydrates, proteins, fats, fiber, vitamins, minerals and water to fulfill requirement of body is called
a)nutrition
b)balanced diet
c)perfect diet
Q.2. MatchColumnA with ColumnB andwrite the correct alphabet inColumnC.
.A balanced diet includes carbohydrates, proteins and fats. a) Name two natural (not processed) sources of dietary carbohydrate.
b)Givetwo uses of proteins in the body.
c) Explain how you would test for the presence of sugar in a food.
Q1.Fill in the blank. 1. We get our energy from fats and ___________________________.2. We use proteins to make cells for _______________________ and repairing the body.3. It is easier for materials to pass through the digestive system if there is ____________________ in our food.4. We also need water, vitamins and ________________________ to be healthy5.The food that contains the most water is ______________________.
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Q.2 Name an enzyme that helps break down: Carbohydrates: __________________________ Proteins: ____________________________Fats: __________________________________
Look at the label from a bar of milk chocolate.
a) How many kJ of energy does this 49g bar give us? ________________________b) Which food groups in the chocolate give us energy? ________________________c) Why do our bodies need energy?
______________________________________________________________________________d) How many kcal of energy does an amount of 200g give us?
_______________________________________Q.3Define digestion. What are the types of digestion? [3]
d) How long does it take food to pass through the digestive system?
e) What is an amylase?
f) What is a biological catalyst?
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g) What happens to starch when it is digested?
h) What is a deficiency disease?
i) Explain why we need dietary fibre in our diet?
Q.2. List FOUR things you need energy for.
Q.3.Explain the meaning of the saying :” you don’t stop exercising because you get older, you get older because you stop exercising.’
Q.4. Label it;
Q1. MCQs.
A. Which juice is rich in iron?
(a) Orange (b) Carrot
(c) Apple (d) Mango
B. Vitamin E is found in
(a) Egg yolk (b) carrots
(c) Mangoes (d) Milk
C. Which of these is a rich source of Vitamin C?
(a) A slice of cheese (b) A cup of orange juice
(c) A medium baked potato (d) A piece of brown bread
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D. A rich source of protein is:
(a) Fish meat (b)Cereal
(c) Palm oil (d) Vegetables
E. Fats simplify into:
(a) Light oil (b) Fatty acids
(c) simple sugars (d) Amino acids
F. Digested food is absorbed through:
(a) artery (b) Villi
(c) Blood (d) Veins
Q2.Fill in the blanks.
i) Main digestion of food takes place in the ________________.
ii) The involuntary wave like contraction by which food is moved through alimentary canal is called
_________________.
iii) The function of large intestines is to absorb _______ and mineral salt.
iv)Fibre provides _________________ to keep intestines working properly.
v) Enzymes are ________________ which speed up chemical reactions.
Q3. Match Column A with Column B and write the correct alphabet in Column C.
Column A Column B Column CVitamin/Minerals Deficiency Problems Correct
Alphabet1. Vitamin A a. Rickets2. Vitamin B1 b. Nerve degeneration3. Vitamin C c. Anemia4. Vitamin D d. High B.P due to excess of
minerals5. Vitamin E e. Night blindness6. Vitamin K f. Beri Beri7. Iodine g. Prolonged bleeding8. Sodium h. Disease of bones9. Iron i. Scurvy
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10. Calcium j. Goitre
Q4a. Distinguish between Physical and Chemical Digestion.
PHYSICAL DIGESTION CHEMICAL DIGESTION
b. If you eat a plain biscuit and chew it for longer period of time it tastes sweet. Explain why._________________________________________________________________________________________________________________________________________________________________________________________________________________________________
c. Fibre is not digested by human beings yet it is an essential part of a balanced diet. Justify.______________________________________________________________________________________________________________________________________________________
Q5. Look at the model of intestines below and answer the questions.
a) What does these substances represent in the model?
i) Visking tubing _____________________
ii) Water _____________________
iii) Starch and Glucose _____________________
iv) Saliva _____________________
Q6. A balanced diet includes carbohydrates, proteins and fats.(a) Name two natural (not processed) sources of dietary carbohydrate.
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_________________________________________________________________(b) Give two uses of proteins in the body.________________________________________________________________
(c) Explain how you would test for the presence of sugar in a food._______________________________________________________________
Q7. This diagram shows the digestive system in the human body.
(a) Name parts A to F (not X or Y).
(b) X is a gland below the mouth. What substance does X secrete?
______________________________
(c) Y is connected to the liver. What substance is stored in Y?
_______________________________
(d) D contains a strong acid. What is the purpose of this acid?
________________________________
(e) What process takes place in B?
________________________________
Q8. This diagram shows a section through the walls of the small intestines.
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(a) What is the name of part A, and what is its purpose?________________________________________________________________________________________________________________________
(b) B is a blood capillary. Why are there blood capillaries in the walls of small intestines?
________________________________________
________________________________________
Q9a. A food contains protein. Describe what happens to this protein after the food reaches the stomach. __________________________________________________________________________________________________________________________________________________________________________
b. Why doesn't the food enter the trachea instead of going to the esophagus? ___________________________________________________________________________________________________________________________________________________________________________________________________________________________
c. Name the enzyme that catalyses the digestion of dietary fats._________________________________________________________________________
d. What are the products of fat digestion?_________________________________________________________________________
e. Name the substance produced by the liver that helps in the digestion of dietary fats._________________________________________________________________________
f. Explain how this substance helps in the digestion of dietary fats._________________________________________________________________________
Q10.This table shows the percentage of starch converted into maltose by a synthetic enzyme, amylase Q, under different conditions.
Temperature(°C)
Percentage of starch converted
pH 3 pH 4 pH 5 pH 6 pH 7 pH8
40 48 67 85 98 81 35
50 37 74 89 96 90 52
60 7 30 96 93 85 46
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70 0 7 40 70 74 30
80 0 0 30 33 28 7
a) What are the optimum conditions for Amylase Q?________________________________________________________________________
b) What is the effect of an increase in temperature on enzyme activity?________________________________________________________________________________________________________________________________________________
Q11. Complete the following.
1 Fish meat ____________ Amino acid
2 ____________ amylase ____________
3 Fat ____________ fatty acid or ____________
4 ____________ mouth ____________ saliva
5 Stomach _____________ digestion.
6 ____________ absorption villi
Q12a. Suggest why fat is considered as a useful constituent of our daily diet?___________________________________________________________________________________________________________________________________________________________________________________________________________________________________b. Mineral salts are required by our body in very small amount yet they are essential. Explain._______________________________________________________________________________________________________________________________________________________________________________________________________________________________________c. What is the role of villi in the small intestines and how does its structure help it to perform its function._______________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Chapter 3 Microbes and DiseasesQ.1.Choose the best answer:
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1. T.B is caused by-------------------
a. Bacteria b. Virus c. fungi d. protozoan
2. Special proteins which can kill bacteria and fungi
a. Alcohol b. Antibiotics c. Disinfectants d. Antiseptic
3. Some of the components of the blood are listed. 1. Antibodies 2. Fibrinogen 3. Platelets 4. plasma
Which of these components are involved in attacking bacteria and other organisms that cause disease?
a. 1 b. 2 c. 4 d. 3
4. Which gas do microorganisms released during the production of bread?
bread
A
B
C
D
Alcohol
Carbon dioxide
hydrogen
Methane
5. New yoghurt can be made by adding a small amount of old yoghurt to some fresh, sterile milk.
What is the name of milk sugar?
a. bacteria b. protein c. lactose d. vitamins
Q.2 Fill in the missing words in the information boxes. The words to use are given below.
Tears nose microbes mucus acid blood
A chemical in your ________kills microbes. Your _______produces mucus which
traps microbes.
Cells in your gullet also produce Skin covers your whole body. It
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______________. stop _____________getting in.
White _________cells destroy microbes. Your stomach contains _________which
kills microbes.
Here are some drawings of different bacteria. Write down the correct name underneath each picture (you do not need to remember the names).
i____________ ii____________
Q.3 (a) Look the drawings below .
a What feature of this bacterium allows it to move?
________________________________________________________________________b Why is it not really correct to call a virus a micro-organism?
Q.4Yeast is a microbe which is added to bread dough. When the yeast cells respire they produce carbon
dioxide which makes the dough rise. Respiration is a chemical reaction that happens in all living cells including yeast cells.
a What sort of microbe is yeast?
_____________________________________________________________________________b Copy and complete this word equation for this process.
glucose + ______________ ______________ ______________ + water (+ energy) Q.5(a).Some white blood cells surround (engulf) microbes and kill them. Others produce antibodies. For each drawing write what is happening. [2] a b
a) _______________________________________________________________________b) _______________________________________________________________________
(b) If you get chickenpox, you will not get it again. Explain why not. ___________________________________________________________________________________
______________________________________________________________Q.1.. Give reasons.
1.If you keep bread in a shopper for several days ,it becomes black. Why
In 1898, a main city gutter line waschoked and contaminated the drinking water .people use this water was suffered with diarrhea andvomiting. About 80,000 population suffered with this onset. Hospitals were over rushed. A panel of doctor decided to know the cause of this out break.
Suppose you are one of the doctor in the panel.1. List 2 factors which come in your mind regarding source of infection.
Q.2. Malaria is a deadly infectious disease and millions of people worldwide are infected every year. How is malaria spread? Hence, suggest how the disease can be controlled.
Q.3. Why it is necessary to finish the whole course of antibiotics prescribed by the doctor even if u no longer feel sick?
Q.4. Food can be preserved through the process of drying. Explain why.
Q.5. What is sewage? Why is it harmful?
Q.6. How do decomposers get their food?
Q.7. Explain why you should bathe or shower regularly.
Q.8 Explain why;
i. Yeast is used in bread making
ii. Never using a towel borrowed from a stranger.
Q.9. The diagram shows some different types of microbes.
Which picture represents a bacterium? Virus? fungus?
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a.______ b.________ c.________
Chapter 9 : Heating and cooling
Q1. Choose the correct answer.
1. What happens to gas when the gas is heated?A. the particles contract B. the particles move further apart C. the particles become denser D. the particles expand2. What is another name for heat energy?A. kinetic energy B. spring energy C. thermal energy D. mechanical energy 3. If you leave a cup of hot tea standing in the kitchen for a whole day, what will happen to its temperature?A. it will stay the same B. it will get only a little bit cooler C. it will end up with the same temperature as the air in the kitchen D. it will be colder then the air in the kitchen4. When one end of a piece of metal is heated?A. the particles get closer together B. the particles vibrate more and the vibrations are passed from particle to particle C. the heat does not move through the metal D. the particles get bigger5. Feathers are good insulators because?A. they are solid B. birds have them C. they trap pocket of air D. they are waterproof6. Which of these materials is a good conductor of heat?A. copper B. airC. water D. glass7. Which surface is a good absorber of heat?A. black surface B.white surfaceC. shiny surface D. shiny black surface8. The S.I unit of temperature is?A. ℉ B.℃C. K D. J9. Which object radiates more energy?A. hotter object B. cooler objectC. shiny object D. brighter object
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10. Sea and land breezes are caused by?A. conduction B. convectionC. radiation D. absorptionQ2. Circle the correct Answer.
1. What happens to gas particles when the gas is heated?a) The particles contractb) The particles move further apartc) The particles become denserd) The particles expand
2. Another name for heat energy is:a) Kinetic energyb) Spring energyc) Thermal energyd) Mechanical energye)
3. If you leave a cup of hot tea standing in the kitchen for a whole day, what will happen to its temperature?
a) It will stay the same.b) It will get only a little bit cooler.c) It will end up the same temperature as the air in the kitchen.d) It will be colder than the air in the kitchen
4.When one end of a piece of metal is heated
a) The particles get closer together.
b) The particles vibrate more and the vibrations are passed from one particle to particle.
c) The heat does not move through the metal.
d) The particles get bigger.5.Feathers are good insulators because
a) They are solidb) They help in flyingc) They trap air in themd) They are water proof
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1.Solar__ (1)__ can convert __(2)__ directly into __(3)__ but they are __(4)__. Dark solar panels fitted in a roof, readily __(5)__ radiation to heat water. A curved __(6)__ can also be used to collect and concentrate the heat radiation to cook food on a barbecue!
2.The diagram shows a simple calorimeter system for measuring the heat given out by a liquid fuel burner. The experiment data for four fuels A,B, C and D is given below. 100 ml (100g) of water was used in the calorimeter to 'collect' the heat given out. The mass of fuel burned and the temperature rise of the water are given.
From the data which fuel is the MOST efficient in terms of energy released per unit mass? [7i-33]
1. mass of fuel = 1.20 g, temperature rise 24oC2. mass of fuel = 1.75g, temperature rise 28oC3. mass of fuel = 0.50 g, temperature rise 9oC4. mass of fuel = 0.80g, temperature rise 12oC
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3.Starting with the solid, the graph shows the results of measuring the temperature of substance X as it was heated from a low to a high temperature. Which of the following is TRUE? [7g-85]
1. X is boiling between times t4 and t52. X is all liquid between times t1 and t23. X is melting between times t2 and t34. temperature TE2 is the boiling point of X
4.The graph shows the results of monitoring a hot liquid pure wax as it slowly cooled to room temperature. Which of the following can you deduce from the results? [7g-96]
1. the freezing point of the wax is temperature T22. from time a to b, the wax is starting to freeze3. from time b to c, the wax is all liquid4. from time c to d, the remaing liquid wax freezes
1. The table shows the melting points and boiling points of some substances A to D. Which substance is a liquid at 30oC?[Substance] Melting Point oC and Boiling Point oC [7g-12]
1. 119 and 4462. -39 and 103. -127 and -334. 15 and 126
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1. Starting with the solid, the graph shows the results of measuring the temperature of substance X as it was heated from a low to a high temperature. Which of the following is TRUE? [7g-81]
1. temperature TE1 is the melting point of X2. X is boiling between times t2 and t33. X is melting between times t0 and t14. X is completely liquid between times t1 and t2
1. Problems can arise with railway steel track from changes in temperature.Small gaps are left between each rail section to allow for changes in length. Which of the following is TRUE about the steel rails and change in temperature? [7g-91]
1. on average the gap will be smaller in the winter than the summer2. expansion happens when the steel atoms lose vibration energy3. on average the rail track will contract more in the summer than the winter4. if no gap is made the rail can get longer becoming dangerously distorted
1. The table below shows the melting points and boiling points of substances A to D. Which substance is a solid at 100oC?[Substance] Melting point oC(mpt), Boiling Point oC(bpt) [7g-27]
1. Butter on a hot plate is seen to be? [7g-38]1. condensing2. boiling3. melting4. Freezing
Q2 a, The diagrams given below show different ways of heat transfer. Name them.
A,
_______________________
B,
_______________________________
C,
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_________________________________
b, Define the three ways of heat transfer . _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Q3, This graph showshow the temperature of pure solid changes asit heated.
Write the correct letter A-F next to each statement.A, This is the melting point of substance ____________B, Where is the substance aliquid? _______________C, Where is the substance formed from regularly arranged molecule? ______________D, Where can the substance be squeezed into a smaller volume?__________________
Q4. Rida pumps up his bicycle tyre. Explain how the air molecule inside the tyre cause pressure._______________________________________________________________________________________________________________________________________________________________________________________________________________________________________Q5. Say it to why?1.Why the tea pots in your kitchen have shiny surface?
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__________________________________________________________________________________________________________________________________________________________ 2. Why fuel storage tanks don’t have black surfaces?__________________________________________________________________________________________________________________________________________________________ 3.Why convection cannot take place in the water if it is heated at the top?_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Q1. Fill in the Blanks.1. In __________________, energy is passed from one particle to another through a medium.
2. Radiation transfers energy in a form of _______________________ which can travel through a
vacuum.
3. In general, solids liquids and gases expand on heating; Liquids expand less whereas,
_____________expands the most.
4. Normal body temperature is______ C.⁰5. The circulating stream of fluid which is set up when heated is called _____________________.
Q3. Give scientific reasons for the following.
a) Solar panels are black in colour.___________________________________________________________________________________________________________________________________________
Ventilation ducts or Air conditioners are always placed at the top of the room.______________________________________________________________________________________________________________________________________________
Double glazed windows help to keep the rooms warm in winter and cold in summer.
a) Describe three methods of Heat Transfer______________________________________________________________________________________________________________________________________________
b) Which of these 3 methods cannot take place in a Vacuum? Why?
Q5.Heat can be transferred by conduction, convection and radiation. How does each of the drawings show heat being transferred?
I. ii.
ii. iv.
Q6.Write down three problems caused by expansion and contraction. How can you overcome theseproblems?
Problems Solutions
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CONDUCTION Example/Non Example and ExplanationWrite your definition of conduction: Egg cooking in a hot pan.
What is happening? When a raw egg begins to fry as it hits a heated frying pan, energy from the pan moves to the egg and cooks it.
Why is this conduction? Example: Heat is transferred through solids from one particle to another particle or from the pan to the egg.
Why is this not an example of convection?
Non Example: It is not convection because heat is not transferred through a fluid (gas or liquid).
Why is this not an example radiation?
Non Example: It is not radiation because heat is not transferred through empty space.
CONVECTION Example/Non Example and Explanation – Complete this sectionWrite your definition of convection:
Hot sand heats the air
What is happening?
Why is this convection? Example:
Why is this not an example of conduction?
Non Example:
Why is this not an example radiation?
Non Example:
RADIATION Example/Non Example and Explanation - Complete this sectionWrite your definition of radiation: Teriburger grilling over charcoal flame
What is happening?
Why is this radiation? Example:
Why is this not an example of conduction?
Non Example:
Why is this not an example of convection?
Non Example:
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A bimetallic strip consists of two metals attached firmly to each other. In the bimetallic strip below, metal X expands at a faster rate than metal W when heated.
(a) If a flame is positioned at two different points of the bimetallic strip, draw in the boxes provided below, how the bimetallic strip will look like after heating.Ken wanted to use the same type of bimetallic strip to construct a fire alarm system for his science project shown below.When the bimetallic strip gets heated up by the fire, it will bend and the two contact point will touch to allow electricity to flow through. This will cause the bell to ring.(b) Ken's teacher commented that there is a mistake in his set-up. Identify the mistake and explain your answer._____________________________________________________________________________
a) The heat from the may cause the metallic railway tracks to .
b) A continuous track without any will be distorted due to expansion. Trains travellingon it may get derailed.
c) Thus, it is necessary to make small in the tracks to allow expansion to occur.
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Refer picture of rolling bridge
a) and
are built with gaps too.
b) They are made such as that one end is fixed and the other is mounted on _.
c) A is left at the roller end of the bridge.
d) This prevents the bridge from being damaged when it or _.
a) _______________and
are hung loosely to make allowance for
b) This prevents the wires and cables to
when they contract on a day
a) Tiled walls and
are usually laid with
b) This prevents the tiles and concrete slabs from
or due to expansion on a hot day.
Q.2In each of the following situations, identify the method of heat transfer taking place (conduction, convection, radiation). More than one process may be occurring.
1. Hot coffee is stirred with a spoon, the spoon gets hot due to _______________.
2. A chair is placed several feet from a fire in a fireplace. The fireplace has a glass screen. The side of the chair facing the fireplace gets warm because of_______________.
3. A certain type of decorative lamp contains colored liquids. These liquids form globs that break off and rise to the top of the liquid. The globs rise due to _______________.
4. Near the ceiling of a room the air is warmer. The warm air rises because of _______________.
5. A college student holds the back of his hand near an iron to see if it is hot. Heat is transferred to his hand by _______________.
6. A heater is placed under one corner of a water bed mattress. Warm water moves throughout the mattress because of _______________.
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7. A certain type of stainless steel cookware has a layer of copper applied to the bottom to help it heat evenly. The copper transfers heat to the pan by _______________.
8. In a swimming pool, the water near the surface is slightly warmer. The warm water rises because of _______________.
9. One end of a copper rod is placed in a flame of a Bunsen burner. Small pieces of wax placed along the rod melt at progressively larger distance from the flame. Heat is transferred through the rod by _______________.
10. A house burns down. On the house across the street, all of the vinyl siding is twisted and warped by the heat. The heat was transferred across the street by _______________.
11. Warm air over the beach rises while cooler dense air from the ocean rushes in due to
_______________.
12. The metal skewer gets so hot that you drop your marshmallow in the campfire because of _______________.
13. A huge rock at the state park gets so hot during the day that you can’t sit on it from_______________.
14. You lay on that same rock at night so that you can keep warm by _______________.
15. A fireman feels a door and it is hot from the fire on the other side due to _______________.
16. The cause of weather systems on earth is _______________.
17. You are in the top bunk of a bunk bed and you want to turn the air conditioner on while your friend on the bottom bunk is fine is caused by _______________.
A bimetallic strip consists of two metals attached firmly to each other. In the bimetallic strip below, metal X expands at a faster rate than metal W when heated.
If a flame is positioned at two different points of the bimetallic strip, draw in the boxes provided below, how the bimetallic strip will look like after heating.Ken wanted to use the same type of bimetallic strip to construct a fire alarm system for his science project shown below.When the bimetallic strip gets heated up by the fire, it
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will bend and the two contact point will touch to allow electricity to flow through. This will cause the bell to ring.(b) Ken's teacher commented that there is a mistake in his set-up. Identify the mistake and explain your answer._____________________________________________________________________________
In each of the following examples, identify whether heat is being transferred through conduction, convection or radiation. Some may have two possible answers. Choose the answer that best fits the situation.
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Q.1Identify the method of heat transfer that takes place in each illustration. Some illustrations may show more than one form of heat transfer.
Q.2In each of the following situations, identify the method of heat transfer taking
place (conduction, convection, radiation). More than one process may be occurring.
1. Hot coffee is stirred with a spoon, the spoon gets hot due to _______________.
2. A chair is placed several feet from a fire in a fireplace. The fireplace has a glass screen. The side of the chair facing the fireplace gets warm because of_______________.
3. A certain type of decorative lamp contains colored liquids. These liquids form globs that break off and rise to the top of the liquid. The globs rise due to _______________.
4. Near the ceiling of a room the air is warmer. The warm air rises because of _______________.
5. A college student holds the back of his hand near an iron to see if it is hot. Heat is transferred to his hand by _______________.
6. A heater is placed under one corner of a water bed mattress. Warm water moves throughout the mattress because of _______________.
7. A certain type of stainless steel cookware has a layer of copper applied to the bottom to help it heat evenly. The copper transfers heat to the pan by _______________.
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8. In a swimming pool, the water near the surface is slightly warmer. The warm water rises because of _______________.
9. One end of a copper rod is placed in a flame of a Bunsen burner. Small pieces of wax placed along the rod melt at progressively larger distance from the flame. Heat is transferred through the rod by _______________.
10. A house burns down. On the house across the street, all of the vinyl siding is twisted and warped by the heat. The heat was transferred across the street by _______________.
11. Warm air over the beach rises while cooler dense air from the ocean rushes in due to
_______________.
12. The metal skewer gets so hot that you drop your marshmallow in the campfire because of _______________.
13. A huge rock at the state park gets so hot during the day that you can’t sit on it from_______________.
14. You lay on that same rock at night so that you can keep warm by _______________.
15. A fireman feels a door and it is hot from the fire on the other side due to _______________.
16. The cause of weather systems on earth is _______________.
17.You are in the top bunk of a bunk bed and you want to turn the air conditioner on while your friend on the bottom bunk is fine is caused by _______________.
1. The SI unit of temperature is
i.⁰C
ii. ⁰F
iii .K
iv. Ampere
Answer C
2. Materials trapped air by fur, feathers, wool and sawdust are thermal
i.insulators
ii.conductors
iii.gainers30
iv.losers
Answer A
3. A solar panel is kept black surface so that it absorbs more
i.heat
ii.water
iii.air
iv.oxygen
4.When state of matter changes temperature
i.increases
ii.decreases
iii.remains same
iii.raised
Q:2.Look at this picture:
It is a:
The normal body temperature is:___________________
The boiling point of water is:______________________
The freezing point of water is:______________________
Q:3.Give reasons:31
i. Why the end of a spoon sticking out of a cup of hot water also gets hot like the end in the hot water?
ii.Why does the liquid in a thermometer rise on a hot day and drop down on a cold day?______________________________________________________________________________________________________________________________________________________
iii.Why a metal knob feels cool when you touch it?______________________________________________________________________________________________________________________________________________________iv.Why plastic or wood are usually used for the handles of these appliances?______________________________________________________________________________________________________________________________________________________
v.Why ventilated ducts and air conditioners are always at the top of the room?______________________________________________________________________________________________________________________________________________________Questions of expansion and contractions are:
Q.1Explain why metals expand on heating?
Q.2Why do gases expand more than solids on heating?
Q.3Why do different liquids expand by different rates when heated?
Q.4Explain why some bridges are fixed on one end and have rollers on the other end?
Q.5Explain why railway lines have gaps between their ends?
Q.6What is the use of thermostat? Name the instrument and explain how it works in an iron?
Q.7Why does hot air balloon rise when heated?
Q.8Why do overhead wire hung loosely?
Q.9Why do most of glassware in the lab is made of Pyrex?
1. Fill in the blank spaces, by choosing the correct words from the list given below : List : large, high, moon, umbra, light, camera, transparent, straight, pass, curvature,convex, shaving, object, enlarged, behind, concave, infinity, principal focus, area, sphere
(i) The bodies which give ......................... energy of their own, are called luminous bodies.
(ii) A ..................... body allows most of the light energy to ................... through it. (iii) A pin
hole ......................... is based on the principle that light travels in......................... lines.
(iv) The shadow cast by earth is very ......................... and can completely cover the whole of ......................... during lunar eclipse.
(v) Birds flying very ......................... do not cast their shadows, as ......................... finishes in air.
(vi) The centre of the hollow ............................. of which the spherical mirror is a part, is called
centre of ............................. .
(vii) Drivers prefer ...................... mirror because it forms an erect, diminished and virtual image close
to the eye and covers a wide ........................... of road behind them.
(viii) Concave mirror is used as ......................... mirror because it forms ........................... erect and
virtual image.
(ix) Image in a plane mirror is as far ............................. as the ............................. is in front of it.
(x) A real, inverted and diminished image is formed in ............................. mirror, when the object
is in between ............................. and the centre of curvature.
(xi) An image diminished to a point and virtual and erect in nature, is formed by convex
mirror, when object is situated at ............................. .
2. Write ‘T’ for true and ‘F’ for false in front of the following statements :(i) The image formed in a pinhole camera, is always erect.
(ii) Light is an invisible energy which causes in us the sensation of vision. (iii) A bird flying high in the sky does not cast its shadow on ground.(iv) Moon is a luminous body in the sky.(v) The size of image in the pinhole camera increases, if the object is moved towards pinhole.
(vi) The light produced by a bulb is called shadowless light. (vii) Convex mirror always forms a virtual image.
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(viii) Concave mirror always forms a real image.(ix) Pole is the centre of sphere of which spherical mirror is a part. (x) In case of plane mirror, the image is of same size as the object.
(xi) Any ray of light passing through the centre of curvature after reflection retraces its path.(xii) Concave mirrors are used as reflectors for street lights.
(xiii) Plane mirror is a better rear-view mirror, as compared to convex mirror. (xiv) Concave mirror is used as shaving mirror, because it makes a better shave. (xv) Dentists use concave mirror, because it is curved and fits well behind teeth. (xvi) When an object is at infinity, the rays coming from it, are always
parallel.
3. Statements given below are incorrect. Write the correct statements.(i) A region of total darkness is called penumbra.
(ii) The image formed by a plane mirror is always inverted.
(iii) Pole of a spherical mirror is the centre of curvature of the mirror.
(iv) Solar eclipse is caused when the sun, the earth and the moon come in straight line, such that the earth is in the middle.
(v) The image formed by a pinhole camera is always virtual, erect and diminished. (vi) Plane
mirror is employed as rear-view mirror in automobiles.
(vii) Two convex mirrors are employed in the construction of a periscope.
(viii) When a ray of light strikes a plane mirror perpendicularly, the angle of incidence is 90°. (ix)A concave mirror forms a virtual image, when an object is between F and C.
(x) A plane mirror can focus solar rays to a point.
4. Match the statements in column A, with those in column B :
Column A Column B
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(i) Distance between the pole and the principal focus of a convex mirror.
(ii) Distance between the pole and centre of curvature of a convex mirror.
(iii) A device used for seeing, over the heads of crowds.
(iv) A mirror used in the solar cookers.(v) A spherical mirror used as a shaving mirror.
(vi) A spherical mirror used as a rear-view mirror. (vii) A reflection in which reflected rays travel as
parallel beam.(viii) A reflection taking place from the walls of a
building(ix) An eclipse formed on the full moon night. (x) An eclipse formed on the new moon day.
5. Tick ( ) the most appropriate answer.(i) A region of total darkness, is called :
(a) penumbra (b) umbra(c) shadow (d) none of these
(ii) A ray of light travelling towards a polished surface is called : (a) normal (b) reflected ray(c) incident ray (d) none of these
(iii) Image formed in a concave mirror is always :(a) inverted (b) erect(c) some times inverted and some times erect(d) none of these
(iv) A medium which almost completely allows the light to pass through them, is called :(a) homogeneous medium (b) hetrogeneous medium(c) translucent medium (d) transparent medium
(v) The image formed by a convex mirror is always : (a) real (b) inverted
(c) enlarged (d) diminished(vi) The image formed by a plane mirror is always :
(a) erect (b) inverted(c) diminished (d) enlarged
(vii) The mirrors used in a periscope are :(a) plane (b) convex(c) concave (d) none of these
(viii) The mirror used as a rear-view mirror, in automobiles, is : (a) plane (b) convex(c) concave (d) none of these
(ix) The mid point of a spherical mirror, is called :(a) aperture (b) centre of curvature(c) pole (d) principal focus
(x) When the angle of incidence is zero, the rays of light strikes a plane mirror at an angle of :(a) zero degree (b) 90°(c) 45° (d) none of these
6. Find the odd one out. Give a reason for your choice.(a) For a plane mirror, the image is always :
(i) real, (ii) erect, (iii) same size as the object,(iv) formed as far behind the mirror as the object is in front of it.
(b) For a convex mirror, the image is always :(i) virtual, (ii) magnified, (iii) erect,
(iv) formed behind the mirror.
(c) For a concave mirror, the image when object is between P and F, is always : (i) virtual (ii) erect, (iii) magnified/diminished,
(iv) formed in front of the mirror.7. (i) What is light?
(ii) By giving four examples each, define the following : (a) Luminous bodies(b) Non-luminous bodies
8. Pick out the luminous and non-luminous bodies from the list given below :
(i) a lighted cigarette, (ii) marble, (iii) dial of watch, (iv) sun, (v) fire flies, (vi) diamond, (vii) red hot iron, (viii) bicycle, (ix) trees, (x) a radio set
11. Draw a neat and labelled diagram to show that light travels in straight lines.
12. (i) What is a shadow?(ii) Name and define two kinds of shadows.
(iii) State three conditions for the formation of shadow.
13. Show the formation of shadows in Figs. 1 and 2 :
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14. By drawing a neat and labelled diagram, show, why flying birds do not cast their shadows. Explain briefly your answer.
15. (i) In the space provided below, are shown the sun, the moon and the earth. Complete a ray diagram to show the formation of eclipse.
(ii) Name the eclipse illustrated by the diagram.
(iii) On which day does this eclipse take place?
(iv) Why does this eclipse last for a very short interval of time? Explain.
16. (i) Draw a neat and labelled diagram of lunar eclipse. (ii) Answer the following questions :
(a) On which day does lunar eclipse take place?
(b) Why is lunar eclipse generally total?38
(c) Why is lunar eclipse a frequent phenomenon?
17. (i) What is the principle of pinhole camera?
(ii) Why is the interior of pinhole camera blackened?
(iii) State three characteristics of an image formed by a pinhole camera.
(iv) How the image formed in a pinhole camera affected, when :(a) Distance between the pinhole and the screen increases? (b) Distance between the pinhole and the screen decreases?
18. (i) What do you understand by the term reflection of light? (ii) By drawing diagrams, define :
(a) Regular reflection(b) Diffused reflection
(iii) State one use each of : (a) Regular reflection
(b) Diffused reflection
(iv) Name four substances, in each case, which cause : (a)
Regular reflection
(b) Diffused reflection
19. Define the following terms with reference to the reflection of light :
(i) Mirror
(ii) Incident ray
(iii) Reflected ray
(iv) Normal
(v) Angle of incidence
(vi) Angle of reflection
(vii) Point of incidence
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20. State two laws of reflection.
21. (i) What do you understand by the following terms?
(a) Real image
(b) Virtual image
(ii) Name the kind of image (real or virtual) formed in case of plane mirror.
22. State four characteristics of an image formed in a plane mirror.
23. (i) A monkey sits at a distance of 4 m from a plane mirror. How much is the distance between the monkey and its image?
(ii) If the monkey moves 1 m towards mirror, how much is the distance between the monkey and its image?
24. Give four practical uses of plane mirrors, other than periscope.
25. What is a reflecting periscope?
26. Define the following terms used for spherical mirrors : (i) Concave mirror
(ii) Convex mirror
Q1. Circle the correct letter for each question.
1 A transparent material is one that …
a light bounces off b. absorbs light
c. light can travel through d. makes light look coloured
2. What happens to light when it hits a mirror?
a. It gets dimmer b. It gets brighter
c. It makes a shadow d. Its direction changes.
3. We can see things in mirrors because …
a. light bounces off the mirror and goes into our eyes b. light from our eyes hits the
mirror.
c. mirrors have a picture of us inside them d. mirrors are transparent.
4. How could you test a piece of material to see if it is good at reflecting light?
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a. Find out if you can see your face in it b. Find out if it is transparent or opaque.
c. Find out if it feels smooth d. Find out if it feels warm
5. A material is good at reflecting light if it is …
a. white b. black c. shiny d. dull
6. You can make something reflect light better if you can …
a. make it smoother b. make it rougher c. make it darker d. heat it up
7. Which is the best way to investigate the factors that could change the size of a shadow?
a. Change the size of the object and its distance from the light source.
b. Change the size of the object and its distance from the screen.
c. Change the distance of the object and the light source from the screen.
d. Change the distance of the object from the screen
Q2. Draw a ray of light on this diagram to show how the boy can see the light bulb. Put an
arrow on your light ray to show which way the light travels.
Q3. Finish drawing the two rays of light to show how the dog makes a shadow on the wall.
Q4. Jenna can see a reflection of herself in a mirror. Draw a ray of light to show how she can
see her feet. Put arrows on your light rays to show which way the light is travelling.
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Medium X
Medium Y
Medium Z
Q17. The diagram shows how light is refracted when traveling through different medium
The above figure shows the registration number LEF 9Z of car J which is following car K. Write down the registration number of car J as seen by the driver of car K in a plane mirror. ___________. What will be the size and type of image formed in this case and why? Q19.Identify the following object as ‘opaque’ ‘transparent’ and ‘translucent’. Give a reason for your choice.
Object Property ReasonClean water
Page of the book
Wooden chair
Air
Q20. The diagram given below shows that light ray is reflected from the mirror label the incident ray, reflected ray , normal , angle of incidence and angle of reflection. Find out the angle of incidence and angle of reflection in the following the given diagram.
Q21. Write down the colours observed at (i) and (ii) when white light passes through the prism.
1. White light is observed when light of _______ wavelengths strike the retina.
2. Primary colors of light are three colors of light which when mixed together produce white light.
There are many different sets of primary light colors. Interestingly enough, the eye contains three
types of color sensors (nerve cells) that sense the entire span of the visible light spectrum. Each of
the three types of cells senses a range of colors; yet they are most sensitive to a specific light color.
The most common set of three primary light colors are those that correspond to the three colors that
the nerve cells are most sensitive to. What are these three primary colors? 44
____________________________________________________________________________3. By combining pairs of these three primary colors in equal intensity, one can produce the secondary
colors of light. State the pairs and the secondary colors they produce. Then fill in the color wheel to
the right.
4. Two lights are arranged above a white sheet of paper. When thelights are turned on they illuminate the entire sheet of paper (as
seen in the diagram at the right). Each light bulb emits a primarycolor of light - red (R), green (G), and blue (B). Depending on
which primary color of light is used, the paper will appear a
different color. Express your understanding of color addition bydetermining the color that the sheet of paper will appear in the
diagrams below.
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5. Complementary colors of light are combinations of two light colors that can be mixed together in
equal intensities to produce white light. Thus, the complementary color of ...
a. ... red light is ____________________ light.
b. ... green light is ____________________ light.
c. ... blue light is ____________________ light.
6. The Rule of Color Subtraction: An understanding of complementary colors assists in
understanding the color appearance of objects when viewed under white light. Whenever an object
subtracts a color from white light, it appears as the complementary color. If an object absorbs cyan
light, then it will appear as red. Conversely, an object that appears as red is an object that absorbs
cyan light. Use these ideas to complete the following statements.
When viewed under white light (RGB), a ...
a. ... red shirt will absorb ________________ light and reflect ________________ light.
b. ... green shirt will absorb ________________ light and reflect ________________ light.
c. ... blue shirt will absorb ________________ light and reflect ________________ light.
d. ... cyan shirt will absorb ________________ light and reflect ________________ light.
e. ... magenta shirt will absorb ________________ light and reflect ________________ light.
f. ... yellow shirt will absorb ________________ light and reflect ________________ light.
g. ... black shirt will absorb ________________ light and reflect ________________ light.
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7. Express your understanding of complementary colors and the rule of color subtraction by completing the following three diagrams. White light (red-green-blue) is shown incident on a sheet
of paper that is painted with a pigment that absorbs one of the primary colors of light. For each
diagram, label the color of the two reflected colors and label the color that the paper appears.
8. The mathematics of color has little to do with numbers and much to do
with the addition and subtraction of colors. The addition of two colors of
light results in a new color. Use the color wheel at the right and the concept
of complementary colors to complete the following color equations. (W =
white; R = red; G = green; B = blue; C = cyan; M = magenta; Y =
yellow)
a. R + G = ______ b. R + B = ______ c. G + B = ______
d. R + C = ______ e. G + M = ______ f. B + Y = ______ g. W - R = ______ h. W - G = ______ i. W - B = ______
j. W - C = ______ k. W - M = ______ l. W - Y = ______
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m. W - R - C = ______ n. W - G - B = ______ o. W - M - G = ______
1. Draw a diagram to show the reflection of light from a plane mirror. Label the following on the diagram:
(a) Plane mirror (b) Incident ray (c) Reflected ray
(d) Point of incidence (e) Normal (f) Angle of incidence
(e) Angle of reflection.
2. How many reflected rays can there be for a given single incident ray falling on a plane mirror?
3. State the Laws of Reflection of Light.
4. An incident ray makes an angle of 75with the surface of a plane mirror. What will be the angle of reflection?
5 A ray of light is incident normally {perpendicularly} on a plane mirror. Where will this ray of light go after reflection from the mirror?
6 What is the difference between regular reflection and diffuse reflection of light?
7 State whether the following statement is true or false :
Diffuse reflection means the failure of the laws of reflection of light.
8 Draw a labeled diagram showing how a plane mirror forms an image of a point object placed in front of it.
9 If an object is placed at a distance of 7.5 cm from a plane mirror, how far would it be from its image?
10 You see your image in a plane mirror? State two characteristics of the image so f o r m e d.
11 Name the phenomenon responsible for the following effect:
When we sit in front of a plane mirror and write with our right hand, it appears in the mirror that we are writing with the left hand.
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12 Fill in the following blanks:
If you touch your------ ear with right hand in front of a plane mirror, it will be seen in the mirror that your right ear is touched with -------
13 How are the two plane mirrors in a periscope arranged?
With respect to one another?
With respect to sides of the tube?
14 Explain how, a hair dresser makes you see hair at the back of your head after the hair cut is complete.
15 How many images of an object will be formed when the object is placed between two plane mirrors which are inclined at the following angles to one another?
{a} 120
{b} 45
{c} 180
{d} 60
{e} 90
16 What will be the number of images formed when an object is placed between two parallel plane mirrors facing each other?
17 Describe the construction of a kaleidoscope.
18 How many plane mirror strips are there in a kaleidoscope? How are they arranged?
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19 State one use of kaleidoscope.
20 What is meant by “dispersion of light “? Name a natural phenomenon which is caused by the dispersion of sunlight in the sky.
21.What are the functions of the following parts of the eye?
a) A shiny metal utensil forms an image, but the image is not clear as that formed by a mirror.
b) You see a clear, bright image of an object in a mirror.
c ) When a mirror is held behind your head after a haircut, not only you see the back of your head, you also see in numerable images of yourself.
23.Answer the following in not more than 20 words.
b. What happens to the rays of light in case of diffuse reflection?
c . An object is placed 20 cm in front of a plane mirror. Where is the image formed? How far is it from the mirror?
24. Answer the following in not more than 100 words.
a. What vision related problems occur when the diet lacks Vitamin A?
b. Describe the structure of the eye with the help of a diagram.
25.Name the form o f energy which enables us to see the objects?
26.What types of waves are light waves?
27.Define a ray of light.
52.How do we see objects?
49.Give any three phenomena shown by light.
64.Why the world AMBULANCE is written as its mirror image in front of the hospital vans?
65.What do you mean by lateral inversion?
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66.Draw a neat and labeled diagram o f human eye.
44.Define a beam o f light?
45.Give an example of be s t reflector of light.
46.What type of image is formed in a plane mirror?
OBJECTIVE
1.Light is a form of ___________ radiation.
(A) Electromagnetic. B) Mechanical. (C) Longitudinal. (D) None o f these.
3.An ________ image canbe obtained o n a screen.
(A) Real . (B) Virtual. (C) Upright. (D) Inverted.
4.According to the laws of reflection:
(A) Angle i = Angle r (B)Angle i not equal to Angle r (C) ) Angle i = Normal (D) All o f these.
5. T h e colour of an object is determined by
(A) T h e colour o f light reflected by it: (B) The colour of light absorbed by it.
(C) The colour o f light incident on it o n l y . (D) None o f the above.
6.Human eye is one o f the most valuable and sensitive organ that:
(A) Enables us to see the wonderful world a n d colours around us.
(B) Can identify the objects.
(C) Is like a camera.
(D) All o f these.
7.T h e ray of light strikes at the surface o f mirror is called:
(A) Reflected ray. (B) Incident ray. (C) Normal ray. (D) None o f these.
8.Wh i c h of the following does not describe working of the human eye?
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(A) Light enters the eye through a thin membrane called the cornea.
(B) Rainbow is formed due to splitting of whi te light.
(C) Iris is a dark muscular diaphragm that controls the size of the pupil for.
(D) Regulating the amount o f light entering into the e y e .
9.E l e c t r i c a l signals generated by light sensitive cells o f retina a r e sent to the brain via:
(A) Mo t o r nerves. (B) Optic nerves. (C) Sensory nerves. (D) Spinal cord.
10.The eye lens forms an ___________ and _________ image of the object on the retina.
(A) Virtual and erect.
(B) Real and inverted .
(C) Real and erect.
(D) Virtual and e r e c t .
11.The transparent front part of eye is called:
(A) Iris. (B) Cornea. (C) Pupil. (D) Cone.
12.Reflection from a rough surface is called:
(A) Regul ar reflection. (B) Diffused reflection. (C) Irregular reflection.
(D) Only (b) & (c).
13.If angl e o f incidence is 3 0 than angle of reflection will be
(A) 6 0
(B) 0
(C) 30
(D) None.
Use these words: absorbs, refraction, reflected, energy, wavelengths, prism, colours
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Light is a form of ___________ that mostly behaves like a wave.White light is made up of different _______________. Different wavelengths give different ___________.You can see the different colours of the rainbow when light passes through water droplets or a glass triangular __________. The different wavelengths bend differently through the water or the glass, which separates the colours. This is called ______________. Colour the diagram!
2. You see different colours according to the wavelengths of light that are absorbed or _____________ from the object you are looking at. For example, a ripe tomato looks red because it reflects the red wavelength of light back to your eyes and __________ the other colours.
3. Match the sentence halves by drawing a line between them.
a A rainbow is made when • the least when passing through the prism.
b Red light bends • it absorbs all light wavelengths except green.
c Violet light bends • light passes through water droplets and refracts into its different wavelengths.
d A lemon looks yellow because • the most when passing through the prism.
e Grass looks green because • it reflects the yellow light back to our eyes.
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The surface of the apple is reflecting the wavelengths we see as red and absorbing all the rest. An object appears white when it reflects all wavelengths and black when it absorbs them all.
Red, green and blue are the additive primary colours of the colour spectrum. Combining balanced amounts of red, green and blue lights also produces pure white. By varying the amount of red, green and blue light, all of the colours in the visible spectrum can be produced.
4. A white box of photographic paper has been written on in large red letters. The box of paper is in a photographic darkroom where the only light is from a RED lamp.
a) What colour does the white box appear
b) What colour does the red writing appear
c) The red lamp is now switched off and a green lamp is switched on.
(i)What colour does the red writing appear in the green light?
(ii)Explain why the writing will appear this colour?
Name that process that split the white light into different colour. Write down the names of the seven colours of a rainbow, in the right order.
When white light is passed through a prism, which colour of light is refracted the most?
When you shine white light into a blue filter:
(a) which colour passes through the filter?
(b) what happens to the other colours?
In terms of the light falling on it;
(a) why is this ink black?
(b) why is the paper white?54
Incident RayAngle of Incidence
Reflected Ray
Angle of Reflection
Mirror
Normal
Reflection and Mirror
When light strikes a surface it is reflected. The light ray striking the surface is called the incident ray. A normal (perpendicular) line is then drawn at the point where the light strikes
the surface. The angle between the incident ray and the normal is called the angle of incidence. The light is then reflected so that the angle of incidence is equal to the angle of reflection. The angle of reflection is the angle between the normal and the reflected light ray. The incident ray, normal, and reflected ray are all in the same plane. The law of reflections states that the angle
of incidence is equal to the angle of reflection.
The law of reflection holds true for any type of surface. Specular or regular reflection occurs when light is reflected from a smooth surface. When parallel light rays strike a smooth surface they are reflected and will still be parallel to each other. If they are parallel to each other, they will all have the same angle of incidence and therefore, the same angle of reflection.
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Diffuse reflection occurs when light is reflected from a rough surface. The word rough is a relative term. The surface can be rough at a microscopic level, for example, an egg is a rough
surface. When parallel light rays strike a rough surface, the light rays are reflected in all directions according to the law of reflection. Since the surface is rough, the parallel light rays will strike the surface with different angles of incidence and therefore they will not all have the
same angle of reflection.
Plane Mirrors have a flat surface. The mirror hanging on the wall in your bathroom is a plane mirror.
In a plane mirror the object is the same size, upright, and the same distance behind the mirror as the object is in front of the mirror. Images in a plane mirror are also reversed left to right.
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Convex
Concave
Real images are images that form where light rays actually cross. In the case of mirrors, that means they form on the same side of the mirror as the object since light can not pass through a mirror. Real images are always inverted (flipped upside down).
Virtual images are images that form where light rays appear to have crossed. In the case of mirrors, that means they form behind the mirror. Virtual images are always upright.
Convex mirrors are made from a section of a sphere whose outer surface was reflective. Convex mirrors are also known as diverging mirrors since they spread out light rays. They are typically found as store security mirrors.
Concave mirrors are made from a section of a sphere whose inner surface was reflective. Concave mirrors are also known as converging mirrors since they bring light rays to a focus. They are typically found as magnifying mirrors
The distance from the center of curvature to the mirror is called the radius of curvature (C). The center of curvature of a curved mirror is located at the center of the sphere from which it was made. The focal point is located halfway between the mirror’s surface and the center of curvature. The focal length is the distance from the focal point to the mirror along the principle axis. The principle axis is a line that passes through both the center of curvature (C) and the focal point (f) and intersects the mirror at a right angle
