#GrowWithGreen

Grade XScience

Mock Test

Mock Test Science Grade - X

General Instructions:

(i) The question paper comprises three sections – A, B and C. Attempt all the sections.

(ii) All questions are compulsory.

(iii) Internal choice is given in each section.

(iv) All questions in Section A are one-mark questions comprising MCQ, VSA type and assertion-reason type questions. They are to be answered in one word or in one sentence.

(v) All questions in Section B are three-mark, short-answer type questions. These are to be answered in about 50 - 60 words each.

(vi) All questions in Section C are five-mark, long-answer type questions. These are to be answered in about 80 - 90 words each.

(vii) This question paper consists of a total of 30 questions.

Section - A

Q1. Give an example of a detergent. (1 Mark)

Q2. Define the modern periodic law. (1 Mark)

Q3. Answer the given questions on the basis of your understanding of the following paragraph and the related studied concepts. (4 Marks) Initially, electricity and magnetism were thought of two different entities. As time passes by, some experiments gave an idea to scientists that these two are related to each other. Experiments by Oersted showed that current-carrying wire produces a magnetic field. After sometime Faraday was another genius who found that not only electric current produces a magnetic field, rather even changing the magnetic field can produce an electric current. This is the basis of an electric generator, which converts mechanical energy into electrical energy. This discovery has many applications like in windmills where the energy of moving wind is converted to electrical energy. (a) State the principle behind the electric generator. (b) How can we find the direction of induced current in the circuit? (c) Which type of current is produced by an electric generator? (d) How can we find the direction of the force on a neutron moving in a magnetic field?

Q4. Study these tables related to the human circulatory system and answer the questions that follow. (4 Marks) Table-A (Chambers of a human heart)

Chambers of a human heart Blood carried by the heart chambers

Right atrium Deoxygenated

Left atrium Oxygenated

Right ventricle Deoxygenated

Left ventricle Oxygenated

Table-B (Blood vessels)

Blood vessels of left part of heart Blood vessels of right part of heart

Pulmonary vein Pulmonary artery

Aorta Vena cava

(a) Which chamber of the heart receives deoxygenated blood from the body? (b) Which blood vessel carries oxygen-rich blood from the lungs? (c) Which of the following statements about the circulatory system of humans is false? (i) The pulmonary vein carries oxygenated blood (ii) The systemic aorta arises from the right ventricle (iii) The pulmonary artery carries deoxygenated blood (iv) The aorta carries blood for the brain and other body parts (d) Which of the following statements provides a correct justification for the high efficiency of closed circulatory system? (i) The oxygenated and deoxygenated blood thoroughly mix with each other. (ii) The blood flows in discrete vessels. (iii) The rate of flow of blood is relatively higher. (iv) Oxygenated and deoxygenated blood are not allowed to mix with each other.

Q5. A mirror has focal length, f = + 10 cm. This mirror is (1 Mark) i) concave mirror ii) convex mirror iii) plane mirror iv) can be a plane mirror or convex mirror OR Identify the incorrect statement: i) Image formed by a concave lens is always virtual. ii) Image formed by a convex lens can be virtual. iii) Magnification of a concave lens is always positive. iv) Magnification of a convex lens is positive when image formed is real.

Q6. An electric fan has power rating 88 W-220 V. When it is operated at 110 V, its resistance is: (1 Mark) i) 275 Ω ii) 550 Ω iii) 1100 Ω iv) 2200 Ω

Q7. The ability of the eye to adjust its focal length is called: (1 Mark) i) least distance of distinct vision ii) power of accommodation iii) persistence of vision iv) ability to contract

Q8. Observe the given diagram and answer the question that follows. (1 Mark)

What effect will be observed when the blood supply to region A is cut off? i) It would be difficult to maintain body posture. ii) The visual senses would become severely impaired. iii) Learning a new language and speech would be affected. iv) General sensations and feelings would be affected. OR Which of the following effects can not be observed due to the non-functioning of pituitary glands? i) Reproductive maturation and development of gametogenesis can be severely affected ii) Growth and metabolic activities can be severely affected.

iii) The extent of skin pigmentation can be affected. iv) The ability to maintain body temperature will be affected.

Q9. Which of the following trends on moving from left to right in a period of the modern periodic table is incorrect? (1 Mark) (i) On moving from left to right in a period, the number of valence electrons present in the elements will increase from 1 to 8. (ii) On moving from left to right in a period, the valency of elements will increase from 0 to 4 and then decrease to 0. (iii) On moving from left to right in a period, the metallic character of elements decreases. (iv) On moving from left to right in a period, the non-metallic character of elements increases.

Q10. Which of the following trends on moving from top to bottom in a group of the modern periodic table is incorrect? (1 Mark) (i) On going down in a group of the modern periodic table, no change is observed in the nature of oxides of the elements. (ii) On going down in a group of the modern periodic table, no change is observed in the valency of the elements. (iii) On going down in a group of the modern periodic table, no change is observed in the number of valence electrons of the elements. (iv) The chemical reactivity of non-metals increases on going down in a group of the modern periodic table.

Q11. The suffix used in the IUPAC name of the given compound is -one. The two atoms

present in the molecule are represented by X and Y. (1 Mark)

The information in which alternative correctly identifies X and Y? (i)X → O; Y → H (ii) X → H; Y → O (iii) X → OH; Y → H (iv) X → H; Y → OH

Q12. Student X, a class 10th student, has been asked to present a seminar on the upcoming day at school. She has been given Mendeleev's Periodic Table as the topic for the seminar. Being a sincere student, she wrote down the entire periodic table given by Mendeleev in her rough notebook in an attempt to memorize the table, a day before the presentation. However, she committed a mistake while placing the oxides of the elements in the right group of the periodic table. Find X's mistake amongst the following mentioned alternatives: (1 Mark) (i) The oxide with the formula RO3 was placed in the III group. (ii) The oxide with the formula R2O was placed in the I group. (iii) The oxide with the formula RO was placed in the II group. (iv) The oxide with the formula RO2 was placed in the IV group. OR Vanshika listed 4 sets (groups) consisting of 3 elements each, after studying Dobereiner's concept of "triads". However one of the listed sets (groups) violates Dobereiner's Law of classification. Identify the set/group amongst the following alternatives that violate Dobereiner's Law of classification. The atomic masses of the elements used by Vanshika have been listed below: (Li : 7, Na : 23, K : 39, Ca : 40, Sr : 88, Ba : 137, Be : 9, Mg : 24, Ca : 40, Si : 28, Cl : 35.5) (i) Li Na K (ii) Ca

Sr Ba (iii) Be Mg Ca (iv) Na Si Cl

Q13. Assertion: Potato chips are packaged with nitrogen gas. (1 Mark) Reason: Nitrogen gas is present in abundance in nature. (i) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion. (ii) Both Assertion and Reason are true but Reason is not the correct explanation of the Assertion. (iii) Assertion is true but Reason is false. (iv) Assertion is false but Reason is true.

Q14. Assertion: A student sitting on the last bench in a classroom is not able to see the teacher's writing on the blackboard clearly. A doctor recommends him a concave lens of proper power. Reason: It is due to high converging power of eye lens or due to an increase in size of an eyeball. (1 Mark) i) Both Assertion and Reason are true and Reason is correct explanation of the Assertion. ii) Both Assertion and Reason are true and Reason is not the correct explanation of the Assertion. iii) Assertion is true but Reason is false. iv) Assertion is false but Reason is true.

Section - B

Q15. Although helium element has 2 valence electrons, it has not been placed in the 2nd group

of the Modern Periodic Table. Give reason for the same. (3 Marks)

Q16. What happens when (3 Marks) (a) copper foil is added to clear solution of silver nitrate. (b) aluminium foil is added to dilute hydrochloric acid solution. OR

Q17.

A metal “X” does not react with water at all. What steps should be followed in the extraction of X from its sulphide ore. Which functional group is present in ethanol? Draw the structure of ethanol. When a piece of sodium metal is added to ethanol, a gas is evolved which burns with a ‘pop’ sound. Name the gas. Write the balanced chemical equation for the reaction. How can ethene be obtained from ethanol? (3 Marks)

Q18. A plant with blue colour flower denoted by BB is cross-breed with a pea plant with white flower denoted by ww. (3 Marks) (a) What is the expected colour of the flowers in their F1 progeny? (b) What will be the percentage of plants bearing white flowers in the F2 generation, when the flowers of F1 plants were selfed? (c) State the expected ratio of the genotype BB and Bw in the F2 progeny. OR Evolution is not always equated with progress. Explain.

Q19. Answer the following questions. (3 Marks)

(a) Label the given figure appropriately in the place of the numbers.

(b) Write one function of each labelled part.

Q20. The given graphical representation shows the variation in levels of UV rays reaching the earth's surface in a particular city X over a duration of four years. (3 Marks)

What is the problem that the city is facing which resulted in the variation in the level of UV radiation? State the reason and possible solutions for the problem.

Q21. (i) Name the three digestive glands present in the human digestive system. (3 Marks) (ii) Name the components of our alimentary canal.

Q22.

(3 Marks) Find the potential drop across resistor R3 in the given circuit. It is given that R1 = 9 Ω, R2 = 18 Ω and R3 = 6 Ω (b) Which uses more energy, a 250-W TV in one hour or a 1200-W toaster in 15 minutes?

Q23. (a) What are the advantages of using LPG as a source of energy? (3 Marks) (b) What is the advantage of solar panels?

Q24. (a) Define principal focus of a concave mirror. (b) A concave mirror of 10 m radius is to be used in a solar cooker. How far must the cooker be placed from the optical centre of the mirror for it to receive maximum solar energy? (3 Marks) OR The near point of a person’s eyes is 2 m. What is the nature and power of the lens required to correct the eye defect?

Section - C

Q25. Label the following reactions according to their types. Give reasons for each type of reaction. (5 Marks)

Q26. Both soap and detergent are the same types of salts. What is the difference between them ? Describe in brief the cleansing action of soap. Why do soaps not form lather in hard water? List two problems that arise due to the use of detergents instead of soaps. (5 Marks) OR Give the IUPAC names of the following:

Q27. Q28. Q29.

(a) Name the human male reproductive organ that produces sperm and also secretes a hormone. Write the functions of the secreted hormone. (b) Draw the diagram of human female reproductive system and label the parts where (i) fertilisation takes place (ii) implantation of the fertilised egg occurs (c) Explain how the embryo gets nourishment inside the mother's body. (5 Marks) (a) Draw a sectional view of the human heart and label on it Aorta, Pulmonary arteries, Vena cava, Left ventricle. (5 Marks) (b) Why is double circulation of blood necessary in human beings? OR (a) Draw the structure of a nephron and label the following on it: Glomerulus, Bowman’s capsule, Renal artery, Collecting duct. (b) What happens to glucose that enters the nephron along with filtrate? The refractive index of ethyl alcohol, carbon disulphide and water are 1.36, 1.63 and 1.33 respectively. In which medium will light travel the fastest? (Speed of light in air = 3×108 m/s) (5 Marks)

Q30. (a) How much work is done in moving a 4 C negative charge across a potential difference of 10 V? (b) Draw the diagram of a circuit that one may use for verifying Ohm’s law. (c) On what basis are materials classified as electrical conductors and electrical insulators? (5 Marks) OR (a) What is Joule’s law of heating? (b) Name two devices that work on the principle of Joule’s heating. (c) An electrical device having a resistance of 10 Ω is connected to a 30 V source. Calculate the amount of heat generated by the device in 10 minutes.

Solutions

1. Sodium n-dodecyl benzene sulphonate is an example of a detergent.

2. According to modern periodic law, the properties of elements are periodic functions of their atomic numbers.

3. (a) An electric generator works on the principle of electromagnetic induction. When a conductor is placed in a varying magnetic field, an emf is induced. (b) The direction of induced current can be found by using Fleming's right-hand rule. The direction of the current induced in a coil (as a result of changing the magnetic field around it) is given by Fleming’s right-hand rule. It states that if the thumb of the right hand points toward the direction of motion of the conductor and the index finger points toward the direction of the magnetic field, then the middle finger indicates the direction of the induced current, provided that all the three fingers are stretched mutually perpendicular to each other, as shown in the given figure.

(c) An electric generator can produce AC or DC current. If full rings are used, we get AC current and if half rings (split rings) are used, we get DC current. (d) Since neutron is a chargeless particle, it will not experience any force, when moving in a magnetic field. Only charged particles experience force, when placed in a magnetic field.

4. (a) The right atrium receives deoxygenated blood from the body. (b) Pulmonary vein carries oxygen-rich blood from the lungs to the heart. (c) (iii) The left side of the human heart carries the oxygenated blood, which is transported by the systemic aorta to various parts of the body. (d) (iv) The closed circulatory system has high efficiency because it does not allow the mixing of oxygenated and deoxygenated blood. Thus, the correct answer is option (iv).

5. When light rays are incident on a convex mirror, after reflection from the mirror, they get diverged. As a result, virtual focus is formed in case of a convex mirror. This focus lies behind the mirror. As all the distances are measured from the pole and the distances measured in the direction of incident light rays are taken as positive.

As focus lies in the direction of incident light rays, focal length in case of convex mirror is taken as positive. Therefore, f = + 10 cm is for convex mirror. Hence, the correct answer is option (ii). OR

For convex lens, when the image is real, it is always inverted. It means magnification would be negative (as image is inverted with respect to object). Hence, the correct answer is option (iii).

6. Given power rating of a fan is 88 W-220 V

Where, V is the applied potential difference and R is the resistance.

As, resistance is a characteristic property, it will not change with change of applied voltage. Hence, the correct answer is option (ii).

7. The ability of the eye to adjust its focal length is called the power of accommodation. Hence, the correct answer is option (ii).

8. Region A represents the cerebellum which is responsible for maintaining body posture. The depletion of blood supply to the cerebellum will make it difficult for an individual to maintain body posture. Hence, the correct answer is option (i). OR The body temperature is regulated by the hypothalamus and non-functioning of the pituitary gland will have minimal or no effects on body temperature. Hence, the correct answer is option (iv).

9. On moving from left to right in a period, the valency of elements will increase from 1 to 4 and then decrease to 0. Hence, the correct answer is option (ii).

10. The chemical reactivity of non-metals decreases on going down in a group of the modern periodic table. Hence, the correct answer is option (iv).

11. The suffix −one is used for ketones. The general formula for ketones is .

Thus, the given compound can only be propanone and it has the following structural formula.

Hence, the correct answer is option (i).

12. The oxide with the formula RO3 must come under the VI group and not the III group, as written by student X. For an element to come under the III group, the formula of its oxide should be R2O3. Hence, the correct answer is option (i). OR For the set of triad mentioned in option D, the average atomic mass of the middle element is not roughly equal to the average of the atomic masses of the other two elements. Thus, it violates Dobereiner's Law of classification.

Hence, the correct answer is option (iv).

13. Nitrogen gas creates an inert atmosphere, thereby preventing oxidation and increasing the shelf life of the chips. This is the reason why potato chips are packaged with nitrogen gas. Therefore, both Assertion and Reason are true but Reason is not the correct explanation of the Assertion. Hence, the correct answer is option (ii).

14. In myopia, a person is not able to see far off objects clearly. It may be due to high converging power of eye lens or due to an increase in the size of an eyeball. An image in this defect is formed in front of the retina. In such a situation, a concave lens of proper power is recommended. Therefore, both assertion and reason are true and reason is the correct explanation of the assertion. Hence, the correct answer is option (i).

15. Although helium element has 2 valence electrons, it is not placed in the 2nd group because its valence shell is completely filled (duplet), and it is an inert gas (highly stable and unreactive monoatomic gas). All elements having a complete valence shell (either duplet or octet) are placed in the last group, i.e., group 18 of the Modern Periodic Table and are called inert gases (noble gases) or zero group elements.

16. (a) On adding copper foil to silver nitrate solution, displacement reaction will take place. In this reaction, copper being more reactive than silver will displace silver from its solution. Silver will get deposited on the copper foil, and the colour of the solution changes from colourless to blue. The balanced chemical reaction for the same has been mentioned below: Cu + 2AgNO3 → Cu(NO3)2 + 2Ag (b) Aluminium metal reacts with dilute hydrochloric acid to form a salt, along with the liberation of hydrogen gas. This is because the reaction of metals with dilute acids yields salt and hydrogen gas. The balanced chemical reaction for the same has been mentioned below: 2Al + 6HCl → 2AlCl3 + 3H2 OR Metal X does not react with water at all. Hence, it is a very less reactive metal (placed below hydrogen in the reactivity series) . Less reactive metals can be extracted from their sulphide ores in the following manner: Steps followed for extraction: 1. Roasting: The sulphide ores are strongly heated in the presence of oxygen, in order to obtain the corresponding metal oxides. It is always easy to extract the metals from their corresponding metal oxides; that is why methods like roasting or calcination are adopted. The balanced chemical reaction of roasting has been mentioned below:

2. Reduction: Metal oxide is then reduced to the metal by further heating.

3. Refining :The metal thus obtained is not very pure. Pure metal can be obtained by the process of electrolytic refining.

17. The functional group present in ethanol is alcohol (−OH). The structure of ethanol is shown below:

The name of the gas which is evolved when a piece of sodium metal is added to ethanol is hydrogen. This reaction also results in the formation of another product i.e., sodium ethoxide. The balanced chemical equation for the given reaction is: 2Na + 2C2H5OH -------> 2C2H5O-Na+ + H2

Ethene can be obtained from ethanol by heating it at 443 K in the presence of excess concentrated sulphuric acid. The balanced chemical equation for the chemical reaction can be written as:

18.

(a) The expected colour of flowers in their F1 progeny is blue. (b) 1/4 of the F2 generation have white flowers. So, we can calculate the percentage as follows: 1/4 × 100 = 25% Hence, the percentage of plants bearing white flowers in F2 progeny is 25. (c) The ratio of the genotype BB and Bw in the F2 progeny is 1 (BB) : 2 (Bw). OR (i) Evolution is not always equated with progress because evolution simply generates diversity, and this diversity helps in better adaptation and survival. (ii) Evolution creates complex body designs, but this does not imply that simpler forms are inefficient. For example, bacteria having simple organisation are more capable of surviving in extreme environments than organisms with complex body designs. (iii) Human beings and chimpanzees have both evolved from a common primate ancestor, but

there is no progress associated with the evolution of chimpanzees. (iv) Human beings should not be considered as the highest evolved species or the climax species. They are only a branch of evolution.

19. (a) In the given figure, I → Hypothalamus II → Pituitary gland III → Midbrain IV→ Medulla (b) Hypothalamus − It is responsible for controlling body temperature, and the expression of emotional reactions. Pituitary gland − It controls and coordinates the endocrine system, and also secretes hormones like the growth hormone. Midbrain − It is concerned with the sense of right handedness and hearing. Medulla − It controls most of the involuntary actions such as heartbeat, blood pressure, etc.

20. It is evident from the graph that the level of UV rays reaching the earth’s surface is increasing. This implies that the ozone layer over the city is depleting. The ozone layer forms a shield over the earth and prevents harmful UV radiation from entering the earth. Reason for ozone depletion − Excessive use of CFCs (chlorofluorocarbons) in refrigerants and fire extinguishers Prevention of ozone depletion - Minimising the use of CFCs and halons

21.

(i) The three digestive glands present in the human body are salivary glands, liver and pancreas. (ii) The components of the human alimentary canal are as follows:

● Buccal cavity ● Food pipe (oesophagus) ● Stomach ● Small intestine ● Large intestine ● Rectum ● Anus

22. (a) Let the equivalent resistance of R1 and R2 be R1.

It is given that, R1 = 9 Ω R2 = 18 Ω

Or, R1 = 6 Ω Hence, the equivalent resistance of the circuit = R1 + R3 = 6 + 6 = 12 Ω

Current flowing through the circuit I

Therefore, current through resistor R3 = 1 A Potential drop across R3, V3 = IR3 = 1 × 6 = 6 V (b) Energy is given by Power × Time. Energy used by TV = 250 × 1 = 250 Wh

Energy used by toaster Therefore, the toaster uses more energy is 15 minutes than the TV does in one hour.

23. (a) The advantages of using LPG are as a source of energy are as follows: 1. Has a high calorific value of about 50 kJ/g 2. Does not cause pollution as it burns with a smokeless flame

3. Does not produce poisonous gases on burning 4. Easy to use and store 5. Neat and clean fuel

(b) Solar panels absorb the sunlight and convert it into electricity. Solar energy is a renewable source of energy and is beneficial for the environment. It is a good alternative for non-renewable sources.

24. (a) The principal focus of a concave mirror is the point on the principal axis on which light rays parallel to the principal axis meet after reflection. (b) To receive maximum solar energy, the cooker must be placed at the focal distance of the mirror. Here, Object distance, u = −∞ Image distance, v = f

Focal length, f , where R = radius of curvature

From mirror formula,

or, v = 5 m The cooker must be placed at 5 m from the optical centre of the mirror. OR Least distance of distinct vision, d = 25 cm Therefore, object distance for clear vision, u = d = −25 cm The near point of the person’s eyes is 2 m. On using the required spectacles, the image distance, v = −2 m = −200 cm

Let the focal length of the spectacle lens be f. On putting these values in the lens formula, we get

25. (a) Oxidation reaction and Combination reaction The given reaction is an oxidation reaction because carbon gains oxygen to form carbon dioxide. It is also a combination reaction as carbon and oxygen combine to form a single compound. (b) Decomposition reaction The given reaction is a decomposition reaction because calcium carbonate decomposes to form two products, namely calcium oxide and carbon dioxide. (c) Displacement reaction The given reaction is a displacement reaction because lead being more reactive than copper, displaces copper from copper (II) chloride in order to form lead chloride solution and copper is deposited on the lead metal. (d) Double displacement reaction and Neutralisation reaction

The given reaction is a double displacement reaction because of the mutual exchange of ions between sodium hydroxide and hydrochloric acid, which leads to the formation of two new compounds, namely sodium chloride and water. It is also a neutralisation reaction, in which an acid reacts with a base to form salt and water, along with the evolution of heat. (e) Double displacement reaction The given reaction is a double displacement reaction because of the exchange of ions between lead nitrate and potassium iodide, which leads to the formation of two new compounds, namely lead iodide and potassium nitrate.

26. Difference between soap and detergents: Soap molecules are sodium or potassium salts of long-chain carboxylic acids. Detergent molecules are ammonium or sulphonate salts of long-chain carboxylic acids. Cleansing action of soaps: When soap is added to water, the hydrophilic ends of the soap molecules remain suspended in water; whereas the hydrophobic ends of the soap molecules attach themselves to the dirt/oil/grease. As a result, a spherical aggregate is formed called as “micelle”. Upon agitation, the micelle removes (pulls out) the dirt from the cloth; and the micelle with dirt trapped inside it, gets dissolved in water. Hence, the dirty cloth gets cleaned.

Soaps do not form lather in hard water: Soap molecules react with calcium and magnesium ions present in hard water to form an insoluble precipitate called scum, which sticks to the cloth and creates hindrance in the

cleansing action of soap. Problems that arise due to the use of detergents instead of soaps are as follows: (a) Being non-biodegradable in nature, detergents cause water pollution. (b) Their entry into the food chain leads to their bioaccumulation in living beings and causes several health issues. OR (i) 1-Butene or But-1-ene

(ii) 2-Methylbutane

(iii) 2-Butyne or But-2-yne

(iv) 3-Methylpentane

(v) Propanal

27.

(a) Testis is the male reproductive organ in humans that produces sperm and also secretes the testosterone hormone. Important functions of testosterone are as follows:

● Stimulates the development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles

● Stimulates muscular growth, growth of facial hair, low pitch voice, sperm production, etc.

(b)

(i) Fertilisation takes place in the fallopian tube (oviduct). (ii) Implantation of the fertilised egg occurs in the uterus. (c) The embryo develops inside the mother’s body for about nine months. Inside the uterus, the

28.

outer tissue surrounding the embryo develops finger-like projections called villi. These villi are surrounded by uterine tissue and maternal blood. They provide a large surface area for the exchange of oxygen and nutrients. There is a special tissue called placenta embedded in the uterine wall. The embryo receives oxygen and nutrients from the mother’s blood via the placenta. The waste material produced by the embryo is removed through the placenta.

(a)

(b) The movement of blood twice through the heart is known as double circulation. Double circulation is necessary in human beings as it allows separation of oxygenated and deoxygenated blood for a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings.

As we know, warm-blooded animals have to maintain a constant body temperature (by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment). Hence, they require more O2 for more respiration, so that they can produce more energy to maintain their body temperature. Thus, the circulatory system of humans is more efficient because of the double circulatory heart.

OR

29.

(a)

(b) The glucose that enters the nephron along with the filtrate is selectively re-absorbed as the urine flows along the tube.

Refractive index of ethyl alcohol = 1.36 Velocity of light in air = 3 × 108 m/s Using the relation,

Refractive index of carbon disulphide = 1.33 Using the relation,

Refractive index of water = 1.33 Using the relation,

Therefore, the speed of light is the fastest in water.

30. (a) We know that

Here, V = Potential difference, W = Work done, C = Charge The potential difference across a point is independent of the nature of charge. It is given that V = 10 V C = 4 C W =? W = V × C = 10 × 4 = 40 J Thus, the work done in moving a 4 C negative change across a potential difference of 10 V is 40 J. (b) The diagram of a circuit that may be used for verifying Ohm’s law can be represented as

(c) Substances are classified as electrical conductors and insulators on the basis of their resistivity. Conductors such as copper have resistivity of the order of 10−8 Ωm, whereas insulators have resistivity of the order of 1010 Ωm or more.

OR (a) Joule’s law of heating shows the relation between the heat produced (H) in a device having resistance (R), when a current (I) flows through it for time (t). RtH = I2 The heat produced in a wire is directly proportional to the

● square of the current (I) flowing in the wire ● resistance (R) of the wire

● time (t) during which the current flows through the wire

(b) Two devices that work on the principle of Joule’s heating are: ● Electric iron ● Safety fuse

(c) Resistance, R = 10 Ω Time, t = 10 min = 10 × 60 = 600 s Applied voltage, V = 30 V From Ohm’s law, we have the relation: V= IR Where I = Current I = R

V AI = 10

30 = 3 Using Joule’s law of heating:

Hence, the heat produced by the given device in 10 minutes is 5.4 × 104 J.