2024 Class 10 Science Paper CBSE: Previous Year Questions with Answers

CBSE Class 10 Science 2024 Board Paper – Questions and Solutions

Class 10 Science Previous Year Question Paper 2024

Series: D4CBA/4 Set– 1 (Code: 31/4/1)

SCIENCE (Set - 1)

★ Please check that this question paper contains 27 printed pages.

★ Please check that this question paper contains 39 questions.

★ Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate.

★ Please write down the serial number of the question in the answer-book before attempting it.

★ 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer-book during this period.

General Instructions :

Read the following instructions very carefully and strictly follow them :

(i) This question paper comprises 39 questions. All questions are compulsory.

(ii) This question paper is divided into five sections A, B, C, D and E.

(iii) Section A Questions No. 1 to 20 are Multiple Choice Questions. Each question carries 1 mark.

(iv) Section B Questions No. 21 to 26 are Very Short Answer type questions. Each question carries 2 marks. Answer to these questions should be in the range of 30 to 50 words.

(v) Section C Questions No. 27 to 33 are Short Answer type questions. Each question carries 3 marks. Answer to these questions should in the range of 50 to 80 words.

(vi) Section D Questions No. 34 to 36 are Long Answer type questions. Each question carries 5 marks. Answer to these questions should be in the range of 80 to 120 words.

(vii) Section E Questions No. 37 to 39 are of 3 source-based/case-based units of assessment carrying 4 marks each with sub-parts.

(viii) There is no overall choice. However, an internal choice has been provided in some sections. Only one of the alternatives has to be attempted in such questions

SECTION – A

Select and write the most appropriate option out of the four options given for each of the questions no. 1 to 20. There is no negative marking for incorrect response. 20 × 1 = 20

The above reaction is a :

(A) Decomposition reaction (B) Displacement reaction

2. An aqueous solution of a salt turns blue litmus to red. The salt could be the one obtained by the reaction of :

(A) and NaOH (B) and KOH (C) and NaOH (D) HCl and

3. Four solutions, namely glucose, alcohol, hydrochloric acid and sulphuric acid filled in four separate beakers are connected one by one in an electric circuit with a bulb. The solutions in which the bulb will glow when current is passed are :

(A) Glucose and alcohol

(B) Alcohol and hydrochloric acid

(D) Hydrochloric acid and sulphuric acid

4. The metals which are found in both free state as well as combined state are :

(A) Gold and platinum (B) Platinum and silver (C) Copper and silver (D) Gold and silver

5. The number of single and double bonds present in a molecule of benzene () respectively, are :

(A) 6 and 6 (B) 9 and 3 (C) 3 and 9 (D) 3 and 3

6. In human beings, when the process of digestion is completed, the

(i) proteins, (ii) carbohydrates, and (iii) fats are respectively finally converted into :

(A) (i) Amino acids, (ii) glucose and (iii) fatty acids

(B) (i) Amino acids, (ii) glucose, (iii) fatty acids and glycerol

(D) (i) Sugars, (ii) amino acids, (iii) fatty acids and glycerol

7. A plant growth inhibitor hormone which causes wilting of leaves is called :

(A) Auxin (B) Cytokinin (C) Abscisic acid (D) Gibberellin

8. The plants that can be raised by the method of vegetative propagation are :

(A) Sugarcane, roses, grapes (B) Sugarcane, mustard, potato

9. The part of seed which is a source of food during germination of seed is :

(A) Cotyledon (B) Radicle (C) Plumule (D) Embryo

10. A zygote is formed by the fusion of a male gamete and a female gamete. The number of chromosomes in the zygote of a human is :

(A) 23 (B) 44 (C) 46 (D) 92

11. Absolute refractive index of glass and water is 2/3 and 3/4 respectively. If the speed of light in glass is m/s , the speed of light in water is :

(A) m/s (B) m/s (C) m/s (D) m/s

12. When a beam of white light passes through a region having very fine dust particles, the colour of light mainly scattered in that region is :

(A) Red (B) Orange (C) Blue (D) Yellow

13. Consider the following combinations of resistors :

Photo

The combinations having equivalent resistance 1Ω is/are :

(A) I and IV (B) Only IV (C) I and II (D) I, II and III

14. An electric iron of resistance 20Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is :

(A) 15000 J (B) 6000 J (C) 1500 J (D) 3000 J

15. A rectangular loop ABCD carrying a current I is situated near a straight conductor XY, such that the conductor is parallel to the side AB of the loop and is in the plane of the loop. If a steady current I is established in the conductor as shown, the conductor XY will

Photo

(A) remain stationary.

(B) move towards the side AB of the loop.

(D) rotate about its axis.

16. Some wastes are given below :

(i) Garden waste

(ii) Ball point pen refills

(iii) Empty medicine bottles made of glass

(iv) Peels of fruits and vegetables

(v) Old cotton shirt

The non-biodegradable wastes among these are :

(A) (i) and (ii) (B) (ii) and (iii) (C) (i), (iv) and (v) (D) (i), (iii) and (iv)

For Questions number 17 to 20, two statements are given one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.

(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

(D) Assertion (A) is false, but Reason (R) is true.

17. Assertion (A) : The extraction of metals from their sulphide ores cannot take place without roasting of the ore.

Reason (R) : Roasting converts sulphide ores directly into metals.

18. Assertion (A) : In the human heart ventricles have thicker muscular walls than atria.

Reason (R) : Ventricles have to pump the blood into various organs.

19. Assertion (A) : Magnetic field lines never intersect each other.

Reason (R) : If they intersect, then at the point of intersection, the compass needle would point towards two directions, which is not possible.

20. Assertion (A) : Oxygen is essential for all aerobic forms of life.

Reason (R) : Free oxygen atoms combine with molecular oxygen to form ozone.

SECTION = B

Questions no. 21 to 26 are very short answer type questions.

21. (a) 1 gram of solid sodium chloride was taken in a clean and dry test tube and concentrated sulphuric acid was added to it.

(i) Name the gas evolved in the reaction.

(ii) What will be observed when this gas is tested with (I) dry, and (II) wet blue litmus paper ? Write your conclusion about the nature (acidic/basic) of this gas. 2

(b) Some metals react with acids to produce salt and hydrogen gas. Illustrate it with an example. How will you test the presence of this gas ? 2

22. Distinguish between a saturated and an unsaturated hydrocarbon by flame test. List the products of combustion reaction of a saturated hydrocarbon. 2

23. (a) We need to water the soil in plants on a regular basis. But it ultimately reaches the leaves of the plant. Explain how this takes place. 2

(b) Name the type of nutrition exhibited by Amoeba. Explain how food is taken in and digested by this organism. 2

24. The survival of a species is promoted through creation of variations. Illustrate with an example. 2

25. A person suffering from presbyopia needs bifocal lens. If he needs two lens of power – 4.0 dioptre and + 2·0 dioptre, which one of these two lenses is for the correction of distant vision and what is its focal length ? 2

26. Two wires A and B of same material, having same lengths and diameters 0·2 mm and 0·3 mm respectively, are connected one by one in a circuit. Which one of these two wires will offer more resistance to the flow of current in the circuit ? Justify your answer. 2

SECTION = C (3M)

Questions no. 27 to 33 are short answer type questions.

27. Write the common name and the chemical name of the compound . Write the method of its preparation. Give chemical equation for the reaction, when water reacts with .

28. Why is the conversion of ethanol to ethanoic acid an oxidation reaction ? Name the oxidising agent used in this conversion. Write chemical equation for this oxidation reaction. How is this reaction different from the reaction in which ethanol burns in the presence of oxygen ? 3

29. (a) Explain with the help of a labelled diagram, the process of reproduction in Hydra by budding. Name the cells used for reproduction in this process.

29. (b) List two roles of each of the following in human reproductive system :

(i) Seminal vesicles and prostate gland

(ii) Oviduct

(iii) Testis

30. List two differences between dominant traits and recessive traits. What percentage of pea plants in the F2 generation were with yellow seeds in Mendel’s cross between the pea plants having yellow (YY) and green coloured (yy) seeds ?

31. Define the term power of accommodation of human eye. What happens to the image distance in the eye when we increase the distance of an object from the eye ? Name and explain the role of the part of human eye responsible for it in this case. 3

32. A student fixes a sheet of white paper on a drawing board. He places a bar magnet in the centre of it. He sprinkles some iron filings uniformly around the bar magnet. Then he taps the drawing board gently and observes that the iron filings arrange themselves in a particular pattern.

(a) Why do iron filings arrange in a particular pattern ?

(b) What does the crowding of iron filings at the ends of the magnet indicate ?

(d) If the student places a cardboard horizontally in a current carrying solenoid and repeats the above activity, in what pattern would the iron filings arrange ? State the conclusion drawn about the magnetic field based on the observed pattern of the lines. [3M]

33. Study the picture given below showing three food chains (a), (b) and (c) and answer the following questions : [3M]

Photo

(a) (b) (c)

(i) Name the type of ecosystems that exist in food chains (b) and (c).

(ii) The first trophic level in all food chains are producers. Why ? What percentage of solar energy do these producers capture for their use ?

(iii) Why are the arrows shown in the diagram in one direction only and not vice versa ? Justify.

SECTION = D [5M]

Questions no. 34 to 36 are long answer type questions.

34. (a) What is a chemical reaction ? Describe one activity each to show that a chemical change has occurred in which (i) change of colour, and (ii) change in temperature has taken place. [5M]

(b) (i) Define a decomposition reaction. How can we say that (I) electrolysis of water, and (II) blackening of silver bromide when exposed to sunlight, are decomposition reactions ? Mention the type of energy involved in each case.

(ii) The type of reactions in which (I) calcium oxide is formed, and (II) calcium hydroxide is formed are opposite reactions to each other. Justify this statement with the help of chemical equations. [5M]

36. (a) The variation of image distance (v) with object distance (u) for a convex lens is given in the following observation table. Analyse it and answer the questions that follow :

S. No.	Objects distance (u) cm	Image distance (v) cm
1	– 150	+30
2	– 75	+37.5
3	– 50	+50
4	– 37.5	+75
5	– 30	+150
6	– 15	+37.5

(i) Without calculation, find the focal length of the convex lens. Justify your answer.

(ii) Which observation is not correct ? Why ? Draw ray diagram to find the position of the image formed for this position of the object.

(iii) Find the approximate value of magnification for u = – 30 cm. [5M]

(b) (i) Define principal axis of a lens. Draw a ray diagram to show what happens when a ray of light parallel to the principal axis of a concave lens passes through it.

(ii) The focal length of a concave lens is 20 cm. At what distance from the lens should a 5 cm tall object be placed so that its image is formed at a distance of 15 cm from the lens ? Also calculate the size of the image formed. [5M]

SECTION = E

The following questions are source-based/case-based questions. Read the case carefully and answer the questions that follow.

37. Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded.

Answer the following questions :

(a) When activity was done with dilute hydrochloric acid, then in which one of the test tubes was the rate of formation of bubbles the fastest and the thermometer showed the highest temperature ? 1

(b) Which metal did not react with dilute hydrochloric acid ? Give reason. 1

(c) (i) Why is hydrogen gas not evolved when a metal reacts with dilute nitric acid ? Name the ultimate products formed in the reaction. 2

(d) (ii) Name the type of reaction on the basis of which reactivity of metals is decided. You have two metals X and Y. How would you decide which is more reactive than the other ? 2

38. Kidneys are vital organs for survival. Several factors like infections, injury or restricted blood flow to kidneys reduce the activity of kidneys. This leads to accumulation of poisonous wastes in the body, which can even lead to death. In case of kidney failure, an artificial kidney can be used. An artificial kidney is a device to remove waste products from the blood through dialysis.

(a) (i) Name the artery that brings oxygenated blood to the kidney.

(ii) Name the cluster the thin-walled blood capillaries present in the Bowman’s capsule. 1

(b) In human excretory system name the organ which stores urine. Is this organ under hormonal control or nervous control ? 1

(d) (ii) In which part of the nephron does selective reabsorption take place ? List the factors which the amount of water reabsorbed depends on. 2

39. Study the following circuit :

Photo

On the basis of this circuit, answer the following questions :

(a) Find the value of total resistance between the points A and B. 1

(b) Find the resistance between the points B and C. 1

(c) (ii) In the above circuit, the 16Ω resistor or the parallel combination of two resistors of 8 Ω , which one of the two will have more potential difference across its two ends ? Justify your answer. [2M]

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Class 10 Science Previous Year Question and Answer 2024

(FOR VISUALLY IMPAIRED CANDIDATES ONLY)

Science , 2024

(I) Please check that this question paper contains 31 printed pages.

(II) Please check that this question paper contains 39 questions.

(III) Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate.

(IV) Please write down the serial number of the question in the answer-book before attempting it.

(V) 15 minute time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer-book during this period.

General Instructions :

Read the following instructions very carefully and strictly follow them :

(i) This question paper comprises 39 questions. All questions are compulsory.

(ii) This question paper is divided into five sections A, B, C, D and E.

(iii) Section A Questions No. 1 to 20 are multiple choice questions. Each question carries 1 mark.

(iv) Section B Questions No. 21 to 26 are very short answer type questions. Each question carries 2 marks. Answer to these questions should be in the range of 30 to 50 words.

(v) Section C Questions No. 27 to 33 are short answer type questions. Each question carries 3 marks. Answer to these questions should in the range of 50 to 80 words.

(vi) Section D Questions No. 34 to 36 are long answer type questions. Each question carries 5 marks. Answer to these questions should be in the range of 80 to 120 words.

(vii) Section E Questions No. 37 to 39 are of 3 source-based/case- based units of assessment carrying 4 marks each with sub-parts.

(viii) There is no overall choice. However, an internal choice has been provided in some sections. Only one of the alternatives has to be attempted in such questions.

SECTION = A

This section has 20 multiple choice questions (Q. No. 1 20). 20 × 1=20

1. A ray of light is incident on a plane mirror at an angle of incidence of 15°. The deviation in the ray produced by the mirror is :

(A) 30° (B) 60° (C) 120° (D) 150°

2. For an object, a convex mirror always forms an image which is :

(A) Virtual, erect and magnified

(B) Virtual, erect and diminished

(D) Real, erect and diminished

3. Two resistors of 1Ω and 3Ω are connected in parallel in a circuit. If a current of 1 ampere is flowing through the circuit, the current flowing through the 3Ω resistor is :

(A) 1·0 ampere (B) 0·75 ampere (C) 0·33 ampere (D) 0·25 ampere

4. Two wires of same metal have the same length but their cross-sectional areas are in the ratio of 4 : 1. They are joined in series. The resistance of the thicker wire is 20 Ω . The total resistance of the combination is :

(A) 25 Ω (B) 100 Ω (C) 16 Ω (D) 340 Ω

5. Consider the following statements :

i. Ciliary muscles adjust for changing the intensity of light entering the eye.

ii. Myopic eye can be corrected by converging lenses of suitable power.

iii. The function of the pupil is to regulate the quantity of light entering the eye.

iv. When ciliary muscles are completely relaxed, the focal length of the eye lens is maximum.

The correct statements are :

(A) i, ii and iv

(B) i, ii and iii

(D) ii and iv

6. Consider the following chemical equations :

To balance this chemical equation the values of the coefficients p, q, r and s must be respectively :

(A) 3, 2, 3, 4 (B) 4, 3, 4, 2 (C) 3, 4, 3, 2 (D) 4, 2, 4, 3

7. The pH of an aqueous solution of a salt is 9. The types of acid and base from which this salt is formed are :

(A) weak acid and weak base

(B) weak acid and strong base

(D) strong acid and strong base

8. A colourless gas G is produced when egg-shells are treated with a solution S. The gas G turns lime water milky. S and G respectively are :

(A) and (B) HCl and (C) NaCl and (D) HCl and

9. The most reactive metal among the following towards cold water is :

(A) Aluminium (B) Potassium (C) Sodium (D) Calcium

10. One mole of a hydrocarbon, on combustion in air, produces two moles of , two moles of and a large amount of heat. This hydrocarbon is :

(A) ethyne (B) ethene (C) ethane (D) methane

11. An organism which breaks down the food material outside the body and then absorbs it is :

(A) Bread mould (B) Cuscuta (C) Lice (D) Tapeworm

12. During respiration, exchange of gases occurs in :

(A) Alveoli (B) Bronchi (C) Larynx (D) Trachea

13. In a nerve cell (neuron), the conversion of electrical signal to chemical signal occurs in/at :

(A) dendritic end (B) cell body (C) axon (D) axonal end

14. The part of a seed that stores food, the future root and the future shoot respectively are :

(A) Plumule, radicle, cotyledon

(B) Cotyledon, plumule, radicle

(D) Radicle, plumule, cotyledon

15. Two pea plants, one round green (RRyy) seeds and another with wrinkled yellow (rrYY) seeds produce F1 progeny that has round yellow (RrYy) seeds. If the F1 progeny plants are selfed, then the minimum number of plants of the F2 progeny will have the following observable characters :

(A) Wrinkled green (B) Wrinkled yellow (C) Round green (D) Round yellow

16. Consider the following groups :

i. Cotton, silk, nylon, leather

ii. Wool, wood, soap, wheat

iii. Banana, cat, rat, tree

iv. Soap, detergent, silk, polyester

The groups of biodegradable material are :

(A) i, ii and iii

(B) ii, iii and iv

(D) ii and iii

For Questions number 17 and 20, two statements are given one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.

(A) Both Assertion (A) and Reason (R) are true and Reason

(R) is the correct explanation of the Assertion (A).

(B) Both Assertion (A) and Reason (R) are true, but Reason

(R) is not the correct explanation of the Assertion (A).

(D) Assertion (A) is false and Reason (R) is true.

17. Assertion (A) : The intensity of the magnetic field produced at the centre of a current carrying circular coil increases on increasing the number of turns in the coil.

Reason (R) : The current that flows in each turn of the coil has the same magnitude and same direction and the magnetic field, due to each turn, just adds up.

18. Assertion (A) : Silver oxide is an amphoteric oxide. Reason (R) : Metal oxides which react with both acids as well as bases are called amphoteric oxides.

19. Assertion (A) : Chromosomes inherited from the parents decide the sex of a child.

Reason (R) : Y chromosome in a male child is inherited from the father.

20. Assertion (A) : Greater number of individuals are present in lower trophic levels of all food chains.

Reason (R) : As the amount of energy decreases at each successive trophic level, larger number of individuals are required at the lower trophic levels to support higher/next trophic levels.

SECTION = B

21. (a) List four properties of the images formed by a plane mirror. 2

(b) Write the definitions of the following terms in the context of a concave mirror : 2

(i) Pole

(ii) Centre of curvature

(iii) Radius of curvature

(iv) Principal axis

22. Write the shape of the magnetic field produced by a current carrying straight conductor. State the rule to find the direction of this field. 2

23. (a) A coumpond ‘X’ on heating at 373K loses water molecules and becomes ‘Y’ . Substance ‘Y’ is used by doctors for supporting fractured bones in the right position.

(i) Identify ‘X’ and ‘Y’ .

(ii) How can we obtain ‘X’ from ‘Y’? 2

(b) Two solutions X and Y give red and blue colour respectively with universal indicator.

(i) In which solution is the hydrogen ion concentration more than the other ? Justify your answer.

(ii) If X and Y are mixed in proper amounts and the resultant mixture is tested with a universal indicator, it turns green. What is the nature of the salt formed ? Justify your answer. 2

24. When a strip of aluminium metal is dipped in a solution of ferrous sulphate, the pale green colour of the solution fades away. State the conclusion you can draw from this observation. Write chemical equation for the reaction that occurs in this case. 2

25. Give reason for the following : 2

(a) Fine hair and mucus are present in the nasal passage.

(b) Rings of cartilage are present in the throat.

26. (a) Name the part of human brain which is responsible for the following actions : 2

(i) Thinking

(ii) Blood pressure

(iii) Maintaining posture and balance

(iv) Salivation

(b) Name the organ/part of a plant which shows : 2

(i) Positive hydrotropism

(ii) Positive phototropism

(iii) Negative geotropism

(iv) Positive chemotropism

SECTION = C

27. (a) (i) How does an electric fuse prevent the circuit and the appliances from possible damage due to short circuiting or overloading ?

(ii) How is the type of current used in household supply different from the one given by dry cells or storage batteries ?

(iii) For distant transmission of electric power, an alternating current (ac) is considered to be advantageous over direct current (dc). Why ? 3

(b) (i) A straight conductor is suspended horizontally with its axis perpendicular to the magnetic field of a strong horseshoe magnet. The conductor gets displaced towards the right when a steady current is passed through it. What will happen to the displacement of the conductor if the :

(1) Polarity of the horseshoe magnet is reversed ?

(2) Direction of current in the conductor is reversed ?

(3) Current through the conductor is increased ?

(ii) Name and state the rule for determining the direction of force on a current carrying conductor placed in a magnetic field. 3

28. When and where does a rainbow appear in the sky ? List the phenomena of light in proper sequence which occurs during the formation of a rainbow. Why can a rainbow not be seen from the surface of the moon ? 3

29. (a) Name and explain the most widely used method for refining impure metals. 3

(b) With the help of chemical equations differentiate between roasting and calcination. How is metal reduced from the product obtained after roasting/calcination of the ore ? Write the chemical equation for the reaction involved. 3

30. Consider the following organic compounds :

(a) Which one of these compounds when heated at 443 K in excess conc. forms ethene as its major product ? State the role of conc. in the reaction. Also, write the chemical equation for the chemical reaction involved.

(b) Give chemical equation for the chemical reaction when and react in the presence of conc. . 3

31. (a) Name the (i) hormone released, and the (ii) gland which secretes it in human beings during scary situations. Explain how our body responds to enable it to deal with such situations. 3

(b) Name the plant growth hormone which is synthesized at the shoot tip. Explain why the shoot of a potted plant bends towards light coming from a window. 3

32. Is it possible that a trait gets inherited, but not expressed ? Give an example to justify your answer. 3

33. (a) What are decomposers ? Explain how the decomposers

(i) keep the environment clean, and also (ii) replenish the soil nutrients. 3

(b) What does a food chain represent ? “The number of trophic levels in a food chain is limited”.Give an example stating reason to justify this statement. 3

SECTION = D

34. (a) (i) Write the relation between resistivity ( ) and resistance (R) for a uniform metallic conductor of length (l) and area of cross-section (A). Use this relation to obtain the SI unit of resistivity.

(ii) The resistance of a metallic wire of 100 m is 20Ω . If the radius of the wire is 5 mm, find the resistivity of the metal of the wire. 5

(b) (i) Obtain an expression for the amount of heat produced in a conductor of resistance R when a steady current I flows through it for a time t.

(ii) An electrical heater of resistance 10 Ω draws a steady current of 5 A from the service mains for 2 hours. Find the power of this heater and the amount of energy consumed by the heater in kilowatt hour. 5

35. Name and explain the process used to obtain sodium hydroxide from the aqueous solution of sodium chloride (Brine). Name the two gases which are given at the anode and the cathode respectively. List two uses of each of these gases. 5

36. (a) (i) What is vegetative propagation ? Is this process sexual or asexual ? Justify your answer.

(ii) List three advantages of practising the process/technique by the farmers.

(iii) Select two plants from the following which are obtained by this technique :

Banana, Papaya, Jasmine, Mustard 5

(b) (i) List two functions each of the following parts of the human female reproductive system :

(1) oviduct (2) uterus (3) ovary

(ii) How does the embryo get nourishment inside the 5

SECTION = E

Q. No. 37 to 39 are source-based/case-based questions with 3 sub-parts. Internal choice is provided in one of these sub-parts.

37. A student has three convex lenses A, B and C of different focal lengths. He wants to observe the images formed by these lenses on a screen by placing a candle flame at different distances as given in following table :

Case No.	Lens	Focal length	Object Distance
1	A	50 cm	25 cm
2	B	20 cm	60 cm
3	C	15 cm	30 cm

(i) List two properties of the image formed by the lens B in case no. 2. 1

(ii) In which one of the three cases given above will the lens form a real image of the same size as the object and why ? 1

(iii) (a) Name the type of lens presented by opticians for the correction of hypermetropia. State the role of such lenses in correcting the vision of the person suffering from this defect. 2

(iii) (b) Use Lens formula to find the distance of the image formed from the optical centre of the lens A in case no. 1. 2

38. Consider the unbalanced chemical equations of a the chemical reactions listed below :

(1)

(2)

(3)

(4)

(i) Select combination reaction from the reactions listed above. Is this reaction endothermic or exothermic ? 1

(ii) Which one of the these reactions represents a displacement reaction ? State the colour change observed in this reaction. 1

(iii) (a) Identify from the above list a reaction in which thermal decomposition occurs. Write the balanced chemical equation to represent thermal decomposition of ferrous sulphate. 2

(iii) (b) Write the word equation for the double displacement reaction given in the above list. Giving reason, state whether this reaction is a redox reaction or not. 2

39. The maintenance functions of every living organism on the earth keeps going on even when they are not doing anything particular. The processes which together perform the job of maintenance of life are known as life processes. These processes are nutrition, respiration, transportation and excretion.

(i) List two types of nutrition. 1

(ii) We eat food. What happens to this food during aerobic respiration in our body ? 1

(iii) (a) What is transpiration ? How is it useful to plants ? 2

(iii) (b) Mention the pathway of urine starting from the organ of its formation. Name any two substances which are reabsorbed from the initial filtrate in the tubular part of the nephron. 2

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Class 10 Science Compartment Previous year Question and Answer 2024

Science , 2024

Series : TYM Set – 1

(I) Please check that this question paper contains 27 printed pages.

(II) Please check that this question paper contains 39 questions.

(III) Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate.

(IV) Please write down the serial number of the question in the answer-book before attempting it.

Time allowed : 3 hours Maximum Marks : 80

General Instructions :

Read the following instructions very carefully and strictly follow them :

(i) This question paper comprises 39 questions. All questions are compulsory.

(ii) This question paper is divided into five sections – A, B, C, D and E.

(iii) Section A – Questions No. 1 to 20 are Multiple Choice Questions. Each question carries 1 mark.

(iv) Section B – Questions No. 21 to 26 are Very Short Answer type questions. Each question carries 2 marks. Answer to these questions should be in the range of 30 to 50 words.

(v) Section C – Questions No. 27 to 33 are Short Answer type questions. Each question carries 3 marks. Answer to these questions should in the range of 50 to 80 words.

(vi) Section D – Questions No. 34 to 36 are Long Answer type questions. Each question carries 5 marks. Answer to these questions should be in the range of 80 to 120 words.

(vii) Section E – Questions No. 37 to 39 are of 3 source-based/case-based units of assessment carrying 4 marks each with sub-parts.

(viii) There is no overall choice. However, an internal choice has been provided in some sections. Only one of the alternatives has to be attempted in such questions.

SECTION = A

Select and write the most appropriate option out of the four options given for each of the questions no. 1 to 20. There is no negative marking for incorrect response. 20 × 1 = 20

1. In the following case(s) the combination reaction occurs in :

II.

III.

IV.

(A) Only III (B) Only IV (C) II and III (D) I, III and IV

2. A few drops of turmeric solution are added to a colourless liquid. If the liquid becomes red, the liquid may be :

(A) Hydrochloric acid (B) Distilled water (C) Ammonium hydroxide (D) Lemon juice

3. The acid present in nettle sting is :

(A) Acetic acid (B) Methanoic acid (C) Tartaric acid (D) Citric acid

4. A hydrocarbon which contains two C-C single bonds and one C≡C triple bond is :

(A) Ethyne (B) Propyne (C) Butyne (D) Benzene

5. When aqueous solutions of barium chloride and sodium sulphate react together, an insoluble substance along with aqueous solution of sodium chloride is formed. This reaction is an example of a :

(A) combination reaction (B) decomposition reaction

6. The name of the compound ‘A’ formed in the following reaction is :

(A) Sodium carbonate

(B) Ammonium carbonate

(D) Ammonium hydrogen carbonate

7. Select the correct statement from the following about the reaction :

(A) CuO is getting oxidised and is getting reduced.

(B) is getting oxidised and CuO is getting reduced.

(D) is an oxidising agent.

8. In the human respiratory system, the path taken by air when we breathe in is :

(A) Nostrils →Larynx →Trachea →Pharynx→ Alveoli

(B) Nostrils →Trachea →Larynx →Pharynx →Alveoli

(D) Nostrils →Larynx →Pharynx →Trachea → Alveoli

9. A doctor advised a person to take an injection of insulin because :

(A) his heart was beating slowly.

(B) his blood pressure was low.

(D) his pancreas was not secreting the required hormone in proper amounts.

10. The movement of sunflowers is in response to a stimulus such as :

(A) gravity (B) chemicals (C) day or night (D) water

11. In bread mould, the structures labelled A and B respectively are :

Photo

(A) hyphae and spore (B) root and sporangium (C) hyphae and sporangium (D) root and spores

12. In plants, waste products like resins and gums are stored in :

(A) leaves that fall off (B) old xylem (C) phloem (D) cellular vacuoles

13. The image formed by a concave mirror of focal length 50 cm is real and of magnification – 1. In this case the distance between the object from its own image is :

(A) 50 cm (B) 100 cm (C) 200 cm (D) Zero

14. When we connect too many electrical appliances to a single socket in a circuit having a fixed value of current rating :

(A) the total resistance of the circuit increases.

(B) the current drawn from the source decreases.

(D) each appliance starts drawing more and more current from the source.

15. Consider the following statements :

I. Every step in a food chain is called a trophic level.

II. Decomposers convert complex inorganic matter in dead remains of organisms into simple substances that go into the soil.

III. In a food chain, energy level increases from lower trophic level to higher trophic level.

IV. Linkages between various food chains constitute a food web.

The correct statements is/are :

(A) I only (B) I and IV (C) I, II and IV (D) II and IV

16. Biomagnification refers to the increase in the :

(A) body weight of an organism.

(B) growth of phytoplanktons.

(D) number of plants and animals in an area.

For Questions number 17 to 20, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.

(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

(D) Assertion (A) is false, but Reason (R) is true.

17. Assertion (A) : Soaps do not form lather (foam) with hard water.

Reason (R) : Hard water has calcium and magnesium salts dissolved in it which on reacting with soap form scum.

18. Assertion (A) : Chemical co-ordination is seen in both plants and animals.

Reason (R) : Plant hormones control directional growth, whereas in animals, growth is never seen in one direction only.

19. Assertion (A) : The commercial unit of electric energy is kilowatt hour (kWh).

Reason (R) :

20. Assertion (A) : Ozone (O3) is a molecule formed by the three atoms of oxygen.

Reason (R) : Ozone shields the surface of the Earth from ultraviolet (UV) radiation from the Sun.

SECTION = B

Questions no. 21 to 26 are very short answer type questions.

21. Define the terms ductility and malleability. Name an element which exhibits both of these properties giving justification for your answer. 2

22. List two ways due to which variations arise in a population. State the importance of variation. 2

23. (a) In the diagram given below, name the labelled parts X and Y. Mention one function for each. 2

Photo

(b) Name the parts of the nervous system which are involved in the following activities : 2

(i) Maintaining body posture

(ii) Salivation

(iii) Hunger

(iv) Answering a question

24. Draw a labelled ray diagram to show the formation of image due to a concave mirror when an object is placed between its pole and principal focus. 2

25. (a) Draw a ray diagram to show the formation of a rainbow in the sky. Mark on the diagram three points A, B and C as given below : 2

A – where dispersion of light occurs

B – where internal reflection of dispersed light occurs

C – where refraction of dispersed light occurs

(b) Name the muscles present in the human eye which enable it to focus on objects at varied distances (i.e., distant as well as nearby objects). Explain how it happens. 2

26. “A vegetarian food habit helps in getting more energy.” Justify the statement. 2

SECTION = C

Questions no. 27 to 33 are short answer type questions.

27. (a) Write a chemical equation for the reaction in which change in colour is observed when a metal is kept immersed in a salt solution of another metal.

(b) When hydrogen gas is passed over heated copper(II) oxide, copper and steam are formed. Write the balanced chemical equation with physical states for this reaction. State what kind of chemical reaction is this. 3

28. (a) What is meant by the term pH of a solution ? The pH of rain water collected from two cities ‘A’ and ‘B’ was found to be 6.1 and 5.3 respectively. The water of which city is more acidic ? Justify your answer. State with reason what would happen to the aquatic life of a pond in which the rain water of city ‘B’ flows. 3

(b) (i) Identify the acid and the base from which the following salts are obtained :

(I) Sodium chloride

(II) Ammonium sulphate

(ii) Write the nature, acidic/basic/neutral, of each of the above mentioned salts, giving reason for your answer. 3

29. (a) Name a part of the flower which (i) persists even after a fruit is formed,

(ii) attracts insects for pollination, (iii) produces pollen grains and

(iv) changes into seed after fertilisation.

(b) After pollination, how does a male germ cell reach the ovary ? Mention the significance of this event. 3

30. A plant having blue coloured flowers (BB) is crossed with a plant having white coloured flowers (bb) :

(a) Name the term used for the trait, which is observed in F1 generation. Give its gene combination.

(b) If the plants obtained in F 1 generation are self-pollinated, write the percentage of (i) plants with flowers of blue colour, and (ii) plants with flowers of white colour in F2 generation. What did the reappearance of plants with white coloured flowers in F 2 generation indicate ? 3

31. In the given circuit when key is closed, determine the following :

Photo

(i) Total resistance offered by the three resistors

(ii) Reading of the ammeter

(iii) Reading of the voltmeter 3

32. (a) State (i) right-hand thumb rule, and (ii) Fleming’s left-hand rule.

(b) Using Fleming’s left-hand rule determine the direction of force experienced by a proton, which enters vertically downwards in a uniform magnetic field acting horizontally from west to east as shown in the diagram.

Photo

33. Draw a ray diagram to show the refraction of a ray of light through a triangular glass prism and mark on it (i) angle of incidence (i), (ii) angle of emergence (e), and (iii) angle of deviation (D). What would happen, if instead of a ray, a beam of white light falls on the prism ? Give reason for the phenomenon that occurs in this case. 3

SECTION = D

Questions no. 34 to 36 are long answer type questions.

34. (a) Write electronic configurations of two elements X (At. no. 12) and Y (At. no. 17). Show the formation of ionic compound when X and Y combine with each other. Write the name and formula of the compound formed. State what would happen if electric current is passed through the aqueous solution of this compound. Name the ion that will reach at (i) cathode, and (ii) anode. 5

(b) (i) Write the name of two metals of moderate reactivity. Which one of the two is more reactive ? How can this fact be demonstrated experimentally in a school laboratory ?

(ii) Some metals of moderate reactivity are also found in the Earth’s crust in the form of their carbonates. Name the processes involved in the extraction of metal from them, giving chemical equations for the reactions that occur. 5

35. (a) (i) Study the diagram below of alimentary canal of man and name the parts marked as A, B and C. Write the name of the enzyme present in each labelled part.

(ii) Explain how digested food reaches each and every cell of the body and is utilised. 5

Photo

(b) (i) Study the diagram below showing schematic representation of transport and exchange of gases in human heart and name the parts labelled as A, B and C. Mention the function of each part.

(ii) Explain how separation of right and left side of the heart is useful for birds. 5

Photo

36. (a) (i) Write the relation between the electrical resistivity ‘ r ’ and the resistance ‘R’ of a cylindrical conductor of length ‘l’ and area of cross-section ‘A’. Use this relationship to determine the SI unit of ‘ r’.

(ii) Find the electrical resistivity of the material of a wire of length 120 cm and diameter 0·4 mm. The resistance of this wire is 3 W . 5

(b) (i) What is meant by heating effect of electric current ? Derive an expression for the amount of heat produced in a conductor of resistance R through which a current I flows for a time t.

(ii) Calculate the amount of heat produced in a conductor of resistance 10 W through which a current of 2 A flows for 100 seconds. 5

SECTION = E

The following questions are source-based/case-based questions. Read the case carefully and answer the questions that follow.

37. Ethanol (commonly known as alcohol) is an important carbon compound widely used in industries, hospitals, etc. Because it is a very good solvent, it is used in medicines such as cough syrups, tincture iodine and many tonics. As it is a cleaner fuel, ethanol is used as an additive in petrol in most of the developed countries of the world.

(a) Write the structure of ethanol. 1

(b) Name the products formed when ethanol burns in sufficient air (oxygen). 1

(c) (i) State what happens when 5% solution of alkaline potassium permanganate is added to warm ethanol. Draw the structure of the product formed and state the role of 5% solution of alkaline potassium permanganate in the reaction. 2

(c) (ii) State what happens when ethanol is heated with excess conc. at 443 K. Draw the structure of the product formed and state the role of conc. in the reaction. 2

38. Plantation drives are often carried out especially during monsoon season for the protection of our environment. Such programmes need a lot of saplings for tree plantation. Plants are propagated by sexual or asexual means in fields and nurseries. Over the years horticulturists have developed asexual methods that use vegetative parts of the plants to multiply. Many plants can reproduce by this method naturally as well as by artificial means.

(a) Which specific part of the plant is used for sexual and asexual means of propagation to produce a new plant ? 1

(b) Give one example of (i) a flower, and (ii) a fruit grown by vegetative propagation. 1

39. In our laboratories we use compound microscopes to see the magnified image of a microscopic object. A compound microscope is made up of two lenses. The lens nearest to the object to be viewed, called objective lens, forms real, inverted and magnified image of the object. This image serves as an object for the second lens called eyepiece. The eyepiece forms virtual, erect and magnified image of its object. Thus, the resultant image formed by a microscope is virtual, inverted and magnified with respect to the microscopic object viewed.

(a) The image of an object formed by a convex lens of focal length 2 cm is real, inverted and magnified. What is the range of object distance in this case ? 1

(b) The image of an object formed by a convex lens of focal length 6 cm is virtual, erect and magnified. What is the range of object distance in this case ? 1

(c) (i) An object is placed at a distance of 12 cm from the optical centre of a convex lens of focal length 18 cm. Draw a labelled ray diagram to show the formation of image in this case. 2

(c) (ii) The image formed by a convex lens is real, inverted and of the same size as the object. If the distance between the objects and the image is 60 cm, determine the focal length of the lens. Give justification for your answer. 2

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Class 10 Science Compartment Previous year Question and Answer 2024

(FOR VISUALLY IMPAIRED CANDIDATES ONLY)

Series : TYM Set – 1

(I) Please check that this question paper contains 27 printed pages.

(II) Please check that this question paper contains 39 questions.

(III) Q.P. Code given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate.

(IV) Please write down the serial number of the question in the answer-book before attempting it.

Time allowed : 3 hours Maximum Marks : 80

General Instructions :

Read the following instructions carefully and follow them :

(i) This question paper contains 33 questions. All questions are compulsory.

(ii) This question paper is divided into five sections – Sections A, B, C, D and E.

(iii) In Section A – Questions no. 1 to 20 are Multiple Choice type questions. Each question carries 1 mark.

(iv) In Section B – Questions no. 21 to 26 are Very Short Answer type questions. Each question carries 2 marks. Answer to these questions should be in the range of 30 to 50 words.

(v) In Section C – Questions no. 27 to 33 are Short Answer type questions. Each question carries 3 marks. Answer to these questions should be in the range of 50 to 80 words.

(vi) In Section D – Questions no. 34 and 36 are Long Answer type questions. Each question carries 5 marks. Answer to these questions should be in the range of 80 to 120 words.

(vii) In Section E – Questions no. 37 to 39 are of 3 source-based/case-based units of assessment carrying 4 marks each with sub-parts.

(viii) There is no overall choice. However, an internal choice has been provided in some sections. Only one of the alternatives has to be attempted in such questions.

SECTION = A

Questions no. 1 to 20 are Multiple Choice type Questions, carrying 1 mark each. 20 × 1 = 20

1. In order to balance the following chemical equation, the values of a, b, c and d respectively are :

(A) 2, 4, 2, 1 (B) 2, 2, 4, 1 (C) 2, 2, 1, 4 (D) 2, 2, 3, 4

2. Select chemical equation of a precipitation reaction from the following :

(A)

(B)

(C)

(D)

3. Identify the pair of natural indicators from the following :

(A) Turmeric and methyl orange

(B) Phenolphthalein and methyl orange

(D) Litmus and methyl orange

4. Identify from the following a compound used in paper, glass and soap industries.

(A) Sodium chloride (B) Bleaching powder (C) Baking soda (D) Washing soda

5. Select a group of unsaturated hydrocarbons from the following :

(A) Ethane, propane, butane (B) Ethyne, butene, cyclohexane

6. In the structure of cyclohexane (C6H12) there are :

(A) Six single bonds, four double bonds and two triple bonds

(B) Six single bonds, two double bonds and one triple bond

(D) Eighteen single bonds only

7. Which one of the following is an example of endothermic process ?

(A) Digestion of food in human body

(B) Formation of slaked lime

(D) Decomposition of silver bromide into silver and bromine

8. Select a pair of plant hormones from the following :

(A) Cytokinin and Insulin (B) Gibberellin and Adrenaline

9. Select from the following the part/parts of a flower which attracts/attract insects for pollination :

(A) Petals only (B) Sepals only (C) Anther and Stigma (D) Petals and Sepals

10. The part of human brain which controls muscular coordination is :

(A) medulla (B) pons (C) cerebrum (D) cerebellum

11. The direction of magnetic field produced around a current carrying straight conductor is determined by using :

(A) Fleming’s left hand rule (B) Left hand thumb rule

12. In a cross between two tall pea plants a few dwarf pea plants were also obtained in F1 generation. It is possible only if the gene combination of the parental plants is :

(A) TT and Tt (B) TT and tt

13. When a steady current flows through a long straight solenoid it behaves as a bar magnet having a north and a south pole. The strength of the magnetic field inside the solenoid is :

(A) zero everywhere.

(B) uniform everywhere.

(D) minimum at the ends and maximum at the centre.

14. You have four resistance wires of same material. Select the wire which will offer the least resistance to the flow of current in an electric circuit :

(A) Length 2l and diameter 2d

(B) Length l and diameter d

(D) Length l/4 and diameter d/4

15. The opening and closing of stomatal pore in the leaves of a plant is due to :

(A) diffusion of carbon dioxide in and out of the guard cells.

(B) movement of water in and out of the guard cells.

(D) stimulus of light in the guard cells.

16. The resistance of a resistor is increased four times its initial value. If other parameters (current and time) remain unchanged, the percentage change in the amount of heat produced in the resistor would be :

(A) 100% (B) 200% (C) 300% (D) 400%

Questions number 17 to 20 are Assertion (A) and Reason (R) based questions. Two statements are given — one labelled Assertion (A) and the other labeled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.

(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

(D) Assertion (A) is false, but Reason (R) is true.

17. Assertion (A) : Magnetic field lines never intersect each other.

Reason (R) : If two field lines intersect each other at a point then it would mean that at the point of intersection the resultant field has two directions, which is not possible.

18. Assertion (A) : In humans, males play an important role in determining the sex of a child.

Reason (R) : Males have two ‘X’ chromosomes.

19. Assertion (A) : Calcium oxide is an amphoteric oxide.

Reason (R) : Metal oxides which react with both acids as well as bases to form salt and water are called amphoteric oxides.

20. Assertion (A) : In humans, the inner lining of the small intestine has finger-like projections called villi which are richly supplied with blood vessels.

Reason (R) : Villi increase the surface area for the absorption of digested food.

SECTION = B

21. ‘‘Ozone, although a deadly poison, performs an essential function for the life on the earth.’’ Justify this statement. 2

22. (a) Write the chemical name and molecular formula of Plaster of Paris. Why should it be stored in a moisture proof container ? 2

(b) What is a neutralisation reaction ? Write the chemical equation for a neutralisation reaction and write the name of the salt produced. 2

23. Write two roles each of (i) bile juice and bile salts and (ii) pancreatic enzymes in the process of digestion. 2

24. What are plant hormones ? Name one plant hormone each responsible for (i) phototropism and (ii) promotion of cell division. 2

25. (a) The far point of a defective eye is nearer than infinity.

(i) Identify the defect of vision.

(ii) List two possible causes responsible for this defect.

(iii) Name the type of lens (converging/diverging) used for the correction of this defect. 2

(b) “The colour of the clear sky from the earth appears blue but the sky appears dark to the passengers flying at very high altitudes.” Explain. 2

26. (a) What is vegetative propagation ? List its two advantages. 2

(b) List two distinguishing features between sexual reproduction and asexual reproduction. 2

SECTION = C

27. Consider the following salts :

(i) XCl (ii) (iii)

Answer the following questions giving reason in each case.

(a) If ‘X’ is sodium, what is the pH of XCl ?

(b) If ‘Y’ is sulphate, what colour would the aqueous solution of give when a few drops of universal indicator are added to it ?

28. In the electrolysis of acidulated water

(a) Name the gas collected at the (i) cathode and (ii) anode.

(b) Why is the volume of one gas collected at one electrode two times the gas collected at the other electrode ?

29. (a) (i) List any two characteristics of lungs which make them an efficient respiratory system.

(ii) Name the part of human respiratory system :

(1) where air is filtered by fine hair and mucus lining.

(2) which separates chest cavity from abdominal cavity.

(3) which has balloon like structures where exchange of gases takes place.

(4) two large air passages which connect trachea to lungs. 3

(b) (i) In the human excretory system name the following parts :

(1) in which urine is produced

(2) where urine is stored

(3) which connects (1) and (2) mentioned above

(4) which provides passage for urine to pass

(ii) List two factors on which the amount of water reabsorbed along the tubular part of nephron depends. 3

30. Explain with the help of a terrestrial food chain how some harmful chemicals enter our bodies through the food chain. Why is the concentration of these harmful chemicals found to be maximum in human beings ? 3

31. (a) A student has focussed the image of an object of height 5 cm on a screen using a convex lens of focal length 20 cm. If the object distance is 30 cm find, using lens formula, the (i) image distance and (ii) height of the image produced. 3

(b) Define power of a lens. The focal length of a lens is + 25 cm. Determine its nature (converging/diverging) and calculate its power. If an object is placed at a distance of 50 cm from the optical centre of this lens, list two properties of the image formed in this case. 3

32. (a) Define the term dispersion of white light. State the colour of light which bends (i) the least, (ii) the most, while passing through a glass prism. Also, state the cause of dispersion of a narrow beam of white light when it passes through a prism. 3

(b) When and where does a rainbow appear in the sky ? Write sequence-wise the phenomena of light responsible for the formation of a rainbow. List two essential conditions for observing a rainbow. 3

33. (a) How is the type of current used in household supply different from the current given by a battery of dry cells ?

(b) Which one of the two currents mentioned above in (a) is considered to be more advantageous for the long distance transmission of electric power and why ?

(c) How does the electric fuse prevent the electric circuit and the appliances from a possible damage due to short circuiting ? 3

SECTION = D

34. (a) (i) Write the name and formula of (1) an alcohol and (2) a carboxylic acid having two carbon atoms.

(ii) If alcohol is X and carboxylic acid is Y, then (1) what happens when X and Y react in the presence of an acid catalyst ? Write chemical equation for the reaction.

(2) what happens when X is heated in excess of conc. sulphuric acid at 443 K ? Write the role of conc. sulphuric acid in the reaction. 5

(b) (i) What are structural isomers ? Write the structures of two isomers of butane.

(ii) Write the name and formula of the simplest saturated hydrocarbon. Write the general formula of the homologous series of carbon compounds in which this compound can be placed. Using this formula, find the 2 nd member of this series. Write chemical equation for the reaction when this simplest hydrocarbon burns in air. 5

35. (a) (i) Write the function of the following parts of a bisexual flower :

(1) stigma (2) pollen tube and (3) anther

(ii) Name the (1) future shoot and (2) future root of a germinating seed.

(iii) Name the parts of the flower that develop into (1) seed and (2) fruit after fertilization. 5

(b) (i) Name the organ that produces sperms as well as secretes hormone in human male reproductive system. Name the hormone it secretes and write its function.

(ii) Name the part of the human female reproductive system where (i) fertilisation occurs and (ii) implantation of zygote takes place.

(iii) Explain how the embryo gets its nourishment inside the mother’s body. 5

36. (a) List two factors on which the resistance of a conductor in the shape of a straight cylinder depends. Write the relation between resistance (R) and the resistivity () of the material of the conductor. Use this relation to obtain the SI unit of resistivity.

(b) Resistance of a metal wire of length 1 m is 40 W . If the area of cross-section of the wire is m² , find the resistivity of the material of the wire. 5

SECTION = E

Note : Q. No. 37 to 39 are source based/case based questions with 3 subparts. Internal choice is provided in one of these subparts.

37. Alloying is a very good method of improving the properties of metals. Most of the metallic objects (cooking utensils, ornaments, coins, guns, etc.) are made up of alloys. It is because pure metals are generally very soft and have low melting points. For example, iron is the most widely used metal, but it is never used in its pure form to make cooking pans because it is very soft in its purest form, it is corrosive and easily stretches when hot.

(a) What is an alloy ? 1

(b) Write the constituents of bronze. 1

(c) (ii) What is solder ? Write its main use stating the property of solder which makes it suitable for this specific use. 2

38. In one of his famous experiments of tracing the inheritance of traits when Mendel cross-pollinated a pure tall pea plant with a pure dwarf pea plant, he got only tall pea plants in the generation. When tall pea plants were self-pollinated, Mendel got generation pea plants in which both tall and dwarf pea plants were present.

(a) List any two pairs of contrasting characters, other than those mentioned above used by Mendel in his experiments. 1

(b) Differentiate between dominant and recessive traits. 1

(c) (i) State the ratio of tall pea plants and dwarf pea plants in generation. Give reason for the appearance of dwarf pea plants in generation. 2

39. Under the guidance of his teacher on a sunny day, a student took a concave mirror of large aperture in his hand and directed its reflecting surface towards the sun. After that he directed the light reflected by the concave mirror on a thick sheet of white paper held close to the mirror. He observed a bright circular spot of light on the paper. Then he moved the mirror back and forth gradually until he got the brightest and smallest spot of light on the paper. The teacher said this sharp spot of light is, in fact, the real and inverted image of the sun and the distance between the mirror and this image is the focal length of this concave mirror.

(a) Define the term principal focus of a concave mirror. 1

(b) If the distance between the pole and focus of a concave mirror is 12 cm, what is the radius of curvature of the mirror ? 1

(c) (i) List two properties of the image formed due to a concave mirror of focal length 15 cm in each of the following cases : 2

(1) object distance 20 cm

(2) object distance 10 cm

(c) (ii) A 3 cm long candle flame is placed in front of a concave mirror. If the distance between the pole and the candle flame is 40 cm and the image is formed at the same place where the candle flame is located, find the 2

(1) focal length of the mirror, and

(2) magnification of the image formed with sign as per the New Cartesian Sign Convention.