2025 Class 10 Science Paper CBSE: Previous Year Questions with Answers

CBSE Class 10 Science 2025 Board Paper – Questions and Solutions

Class 10 Science Previuos Year Question and Answer 2025

SCIENCE (Set - 1)

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

★ 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 check that this question paper contains 39 questions.

★ Please write down the Serial Number of the question 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.

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. Electrolysis of water is a decomposition reaction. The mass ratio (MH : MO) of hydrogen and oxygen gases liberated at the electrodes during electrolysis of water is :

(A) 8 : 1 (B) 2 : 1 (C) 1 : 2 (D) 1 : 8

2. The products formed when Aluminium and Magnesium are burnt in the presence of air respectively are :

(A) and (B) and MgO (C) and MgO (D) and

3. The following table shows the pH values of four solutions A, B, C and D on a pH scale:

Photo

The solutions A, B, C and D respectively are of a

(A) Strong acid, weak acid, neutral, strong base

(B) Weak acid, neutral, weak base, strong base

(D) Weak acid, neutral, strong base, strong acid

4. Consider the following reactions :

(i) Dilute hydrochloric acid reacts with sodium hydroxide.

(ii) Magnesium oxide reacts with dilute hydrochloric acid.

(iii) Carbon dioxide reacts with sodium hydroxide.

It is found that in each case :

(A) Salt and water is formed.

(B) Neutral salts are formed.

(D) Acidic salts are formed.

5. Reaction between two elements A and B, forms a compound C. A loses electrons and B gains electrons. Which one of the following properties will not be shown by compound C ?

(A) It has high melting point.

(B) It is highly soluble in water.

(D) It conducts electricity in its molten state or aqueous solution.

6. The metals obtained from their molten chlorides by the process of electrolytic reduction are :

(A) Gold and silver

(B) Calcium and magnesium

(D) Sodium and iron

7. The formation of magnesium oxide is correctly shown in option :

Photo

8. Secretion of less saliva in mouth will effect the conversion of :

(A) proteins into amino acids

(B) fats into fatty acids and glycerol

(D) sugars into alcohol

9. The plant hormone whose concentration stimulates the cells to grow longer on the side of the shoot which is away from light is :

(A) Cytokinins

(B) Gibberellins

(D) Auxins

10. The correct/true statement(s) for a bisexual flower is/are :

(i) They possess both stamen and pistil.

(ii) They possess either stamen or pistil.

(iii) They exhibit either self-pollination or cross-pollination.

(iv) They cannot produce fruits on their own.

(A) (i) only (B) (iv) only

11. If pea plants with round and green seeds (RRyy) are crossed with pea plants having wrinkled and yellow seeds (rrYY), the seeds developed by the plants of F1 generation will be :

(A) 50% round and green (B) 75% wrinkled and green

12. The breakdown of glucose has taken the following pathway :

Glucose Pyruvate + Energy Lactic acid + Energy

The sites ‘a’ and ‘b’ respectively are :

(A) Mitochondria and Oxygen deficient muscle cells

(B) Cytoplasm and Oxygen rich muscle cells

(D) Cytoplasm and Oxygen deficient muscle cells

13. Mirror ‘X’ is used to concentrate sunlight in solar furnace and Mirror ‘Y’ is fitted on the side of the vehicle to see the traffic behind the driver. Which of the following statements are true for the two mirrors ?

(i) The image formed by mirror ‘X’ is real, diminished and at its focus.

(ii) The image formed by mirror ‘Y’ is virtual, diminished and erect.

(iii) The image formed by mirror ‘X’ is virtual, diminished and erect.

(iv) The image formed by mirror ‘Y’ is real, diminished and at its focus.

(A) (i) and (ii) (B) (ii) and (iii)

14. An old person is suffering from an eye defect caused by weakening of ciliary muscles and diminishing flexibility of the eye lens.If the defect of vision is ‘a’ which can be corrected by lens ‘b’, then ‘a’ and ‘b’ respectively are:

(A) hypermetropia and convex lens

(B) presbyopia and bifocal lens

(D) myopia and bifocal lens

15. Which of the following groups do not constitute a food chain ?

(i) Wolf, rabbit, grass, lion

(ii) Plankton, man, grasshopper, fish

(iii) Hawk, grass, snake, grasshopper, frog

(iv) Grass, snake, wolf, tiger

(A) (i) and (iv) (B) (i) and (iii)

16. The percentage of solar energy which is not converted into food energy by the leaves of green plants in a terrestrial ecosystem is about :

(A) 1% (B) 10% (C) 90% (D) 99%

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) : Decomposition reactions are generally endothermic reactions.

Reason (R) : Decomposition of organic matter into compost is an exothermic process.

18. Assertion (A) : A human child bears all the basic features of human beings.

Reason (R) : It looks exactly like its parents, showing very little variations.

19. Assertion (A) : No two magnetic field lines are found to cross each other.

Reason (R) : The compass needle cannot point towards two directions at the point of intersection of two magnetic field lines.

20. Assertion (A) : The amount of ozone in the atmosphere began to drop sharply in the 1980s.

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

SECTION = B

Questions no. 21 to 26 are Very Short Answer Type questions.

21. A student performs the following experiment in his school laboratory.

Photo

List two observations to justify that in this experiment a chemical change has taken place. 2

22. Draw labelled diagrams to show different stages of budding in Hydra. 2

23. (a) Besides minimising the loss of blood, why is it essential to plug any leak in a blood vessel ? Name the component of blood which helps in this process and state how this component perform this function. 2

23.(b) (i) The transport system in plants is relatively slower than in animals. Give reasons.

(ii) State the role of phloem in the transport of materials in plants. [2M]

24. An object is placed at a distance of 60 cm from a concave lens of focal length 30 cm. Use lens formula to find the position of the image formed in this case. 2

25. (a) A wire of resistance R is cut into three equal parts. If these three parts are then joined in parallel, calculate the total resistance of the combination so formed. 2

(b) Define electric power. When do we say that the power consumed in an electric circuit is 1 watt ? 2

26. ‘‘Excessive use of chemicals and pesticides in agriculture adversely effect the environment.’’ Justify this statement. [2M]

SECTION = C

Questions no. 27 to 33 are Short Answer Type questions.

27. (a) ‘‘Displacement reactions also play a key role in extracting metals in the middle of the reactivity series.’’ Justify this statement with two examples.

(b) Why can metals high up in the reactivity series not be obtained by reduction of their oxides by carbon ? 3

28. (a) With the help of an activity, explain the conditions under which iron articles get rusted. 3

(b) (i) Name two metals which react violently with cold water. List any three observations which a student notes when these metal are dropped in a beaker containing water.

(ii) Write a test to identify the gas evolved (if any) during the reaction of these metals with water. 3

29. Plants have neither a nervous system nor muscles, even then they respond to stimuli. For example, the leaves of chhui-mui (touch-me-not) plant when touched begin to fold up and droop.

(a) How is the information communicated in ‘‘touch-me-not’’ plants ?

(b) What enables the plant cells to bring out the observable response ?

30. (a) What are chromosomes ?

(b) Explain in brief how stability of DNA content of a species is ensured in sexually reproducing organisms ? 3

31. Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when the object is placed (i) at infinity and (ii) between infinity and pole P of the mirror. 3

32. Consider the following electric circuit :

Photo

Calculate the values of the following : 3

(a) The total resistance of the circuit

(b) The total current drawn from the source

33. (a) Write the relationship between resistivity and resistance of a cylindrical conductor of length l and area of cross-section A. Hence derive the SI unit of resistivity.

(b) Why are alloys used in electrical heating devices ? 3

SECTION = D

Questions no. 34 to 36 are Long Answer Type questions.

34. (a) (i) Draw two isomeric structures of Butene ().

(ii) Name the following compounds :

(I)

H H H H

| | | |

H – C – C – C – C – Cl

| | | |

H H H H

(II) H H H

| | |

H – C – C – C – C – H

| | || |

H H O H

(iii) Write the chemical equations for the following reactions. Mention one essential condition each for these reactions to take place.

(I) Ethanol undergoes complete oxidation

(II) Propene undergoes hydrogenation

(III) Ethanoic acid reacts with ethanol [5M]

(b) (i) A carbon compound X is a good solvent. On reaction with sodium, X forms two products Y and Z. Z is used to convert vegetable oil into vegetable ghee. Identify and name X, Y and Z. Also write the equation of reaction of X with sodium to justify your answer.

(ii) Write chemical equation to show what happens when ethanol :

(I) burns in oxygen/air.

(II) is heated at 443 K in excess conc. .

(III) reacts with acidified potassium dichromate. 5

35. (a) (i) Write the functions of the following parts of human female reproductive system :

(I) Ovary

(II) Fallopian tube

(III) Uterus

(ii) State briefly two contraceptive methods used by human males. 5

(b) (i) Differentiate between self-pollination and cross-pollination.

(ii) Identify A, B and C in the diagram given below and write one function of each.

Photo

36. (a) (i) The power of a lens ‘X’ is – 2·5 D. Name the lens and determine its focal length in cm. For which eye defect of vision will an optician prescribe this type of lens as a corrective lens ?

(ii) ‘‘The value of magnification ‘m’ for a lens is – 2.’’ Using new Cartesian Sign Convention and considering that an object is placed at a distance of 20 cm from the optical centre of this lens, state :

(I) the nature of the image formed;

(II) size of the image compared to the size of the object;

(III) position of the image, and

(IV) sign of the height of the image.

(iii) The numerical values of the focal lengths of two lenses A and B are 10 cm and 20 cm respectively. Which one of the two will show higher degree of convergence/divergence ? Give reason to justify your answer. 5

(b) (i) Draw a ray diagram to show the refraction of a ray of light through a rectangular glass slab when it falls obliquely from air into glass.

(ii) State Snell’s law of refraction of light.

(iii) Differentiate between the virtual images formed by a convex lens and a concave lens on the basis of :

(I) object distance, and

(II) magnification. [5M]

SECTION = E

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

37. Seawater contains many salts dissolved in it. Common salt is separated from these salts. Deposits of solid salt are also found in several parts of the world. These large crystals are often brown due to impurities. This is called rock salt and is mined like coal. The common salt is an important raw material for chemicals of daily use.

(a) Write balanced chemical equations to show the products formed during electrolysis of brine. 1

(b) List two uses of any one product obtained during electrolysis of brine. 1

(c) (i) A mild non-corrosive basic salt ‘A’, used for faster cooking, is strongly heated to produce a compound ‘B’, that is used for removing permanent hardness of water. Identify A and B and also write the equation for the reaction that occurs when A is heated. 2

38. The maintenance functions of all living organisms must go on even when they are not doing anything particular. Even when we are just sitting in a class or even asleep, this maintenance job has to go on. These maintenance processes require energy to prevent damage and break-down of cells and tissues, which is obtained by the individual organism from the food prepared by the autotrophs, called producers.

(a) Name and define the process by which green plants prepare food. 1

(b) Write chemical equation involved in the above process. 1

(I) during cloudy weather, and

(II) when stomata get blocked due to dust.

39. In our homes, we receive the supply of electric power through a main supply also called mains, either supported through overhead electric poles or by underground cables. In our country the potential difference between the two wires (live wire and neutral wire) of this supply is 220 V.

(a) Write the colours of the insulation covers of the line wires through which supply comes to our homes. 1

(b) What should be the current rating of the electric circuit (220 V) so that an electric iron of 1 kW power rating can be operated ? 1

(c) (i) What is the function of the earth wire ? State the advantage of the earth wire in domestic electric appliances such as electric iron. 2

(c) (ii) List two precautions to be taken to avoid electrical accidents. State how these precautions prevent possible damage to the circuit/appliance. 2

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Class 10 Science Previous Year Question and Answer 2025

(FOR VISUALLY IMPAIRED CANDIDATES ONLY)

Science , 2025

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

(II) 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.

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

(IV) Please write down the Serial Number of the question in the answer-book at the given place 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 candidates will read the question paper only and will not write any answer on the answer-book during this period.

Time allowed : 3 hours Maximum Marks : 80

General Instructions :

Read the following instructions very carefully and strictly follow them :

(i) This question paper comprises of 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 be 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

1. A student has dipped some iron nails in an aqueous solution of copper sulphate. After about 25 minutes, he would observe that the colour of the solution has changed from:

(A) blue to colourless

(B) blue to pale green

(D) pale green to colourless

2. In case of wires of same resistivity, the resistance of the wire will be maximum if the diameter and length of the wire respectively are

(A) D and L (B) D/2 and L/4 (C) D/3 and L/6 (D) D/4 and L/12

3. Select from the following a metal which does not react with cold as well as hot water:

(A) Calcium (B) Iron (C) Magnesium (D) Sodium

4. Select ionic compounds from the following:

(a) CCl₄ (b) KCl (c) HCl (d) NaCl

(A) (b) and (c)

(B) (c) and (d)

(D) (b) and (d)

5. The products obtained when sodium reacts with ethanol are:

(A) Sodium ethoxide and hydrogen

(B) Sodium ethoxide and oxygen

(D) Sodium ethanoate and hydrogen

6. The functional group present in butanone is:

(A) –CHO (B) –COOH (C) –OH (D) >C=O

7. Movement of soluble product of photosynthesis in plants from leaves to other parts of the plant takes place mainly through:

(A) Tracheids (B) Sieve tubes (C) Vessels (D) Companion cells

8. The substances that are selectively reabsorbed from the tubular part of the nephron as the urine flows through it are:

(A) amino acids and salts only

(B) amino acids, salts, glucose and water

(D) water, amino acids and glucose

9. A voluntary action such as writing on a paper is controlled by the part of brain called:

(A) Cerebrum (B) Cerebellum (C) Pons (D) Medulla

10. The plant part/parts having greater concentration of cytokinins is/are:

(A) fruits only (B) leaves (C) fruits and seeds (D) seeds and leaves

11. Vegetative propagation refers to the production of new plants of the same species from the following parts of a plant:

(A) stem, flower and fruit

(B) roots, stem and flower

(D) roots, stem and leaves

12. An object is placed at a distance of 30 cm from the reflecting surface of a concave mirror of radius of curvature 40 cm. The image formed is:

(A) Virtual and magnified (B) Virtual and diminished

13. A steady current flows through a thick horizontal straight wire from east to west. The direction of the magnetic field produced at a point above the wire is towards:

(A) North (B) South (C) East (D) West

14. When we focus our eyes on a distant object, the ciliary muscles of our eyes are relaxed. In this case the eye lens becomes:

(A) thin and its curvature is maximum.

(B) thin and its curvature is minimum.

(D) thick and its curvature is maximum.

15. The resistance of a wire is 40 Ω. If 2 A of current flows through this wire for 50 seconds, the heat produced in the wire is:

(A) 4000 J (B) 8000 J (C) 16000 J (D) 80000 J

16. A uniform magnetic field:

(A) always exerts a force on a current carrying conductor.

(B) never exerts a force on a current carrying conductor.

(D) exerts a force only when current flows through a conductor at right angles to the field.

Question numbers 17 to 20 consist of two statements — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the options (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 Assertion (A).

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

17. Assertion (A): Sodium chloride and potassium chloride are neutral salts.

Reason (R): The pH of these salts is 7.0 .

18. Assertion (A): Variations are seen in offsprings produced by sexual reproduction.

Reason (R): DNA copying in a reproducing cell is not completely accurate.

19. Assertion (A): The colour of the scattered light depends on the size of the scattering particles.

Reason (R): Very fine particles scatter mainly red light while particles of larger size scatter light of shorter wavelengths.

20. Assertion (A): An electric fuse wire is always connected in parallel with the mainline.

Reason (R): If an electric current larger than the rated value flows through the electric circuit, the fuse wire melts.

SECTION = B

Question Nos. 21 to 26 are very short answer questions.

21. (a) What is observed when an aqueous solution of sodium sulphate is added to an aqueous solution of barium chloride taken in a test tube? Write chemical equation for the reaction that occurs and name the type of reaction.

(b) Write the change in colour that occurs when crystals of ferrous sulphate are heated strongly. Give chemical equation for the reaction that occurs and also name the type of reaction.

22. Zinc granules are added to dil. H₂SO₄ taken in a test tube. List two changes that are observed in this case. Write chemical equation for the reaction.

23. Where does exchange of gases occur in plants? 2

24. (a) Write the role of the following in the process of digestion in human beings:

(i) Salivary amylase (ii) Hydrochloric acid (iii) Trypsin (iv) Intestinal villi

(b) How does blood come back to the heart from different parts of the body?

25. (a) List four properties of the images formed by plane mirrors.

(b) List four properties of the images formed by convex mirrors when objects are placed anywhere in front of their reflecting surfaces.

26. (a) Define the term 'biodegradable waste'. Select biodegradable waste(s) from the following:

Insecticides, agricultural waste, plastics, sewage .

(b) Why are bacteria and fungi called decomposers? List any two advantages of decomposers.

SECTION = C

Question Nos. 27 to 33 are short answer questions.

27. (a) In the process of electrolysis of water:

(i) Name the gas collected at (1) cathode and (2) anode.

(ii) Why is the volume of the two gases not the same?

(iii) What would happen if dil. HCl is not added to water?

(b) Write balanced chemical equation for each of the following reactions:

(i) Sodium metal reacts with water to produce sodium hydroxide and hydrogen gas.

(ii) Lead nitrate is heated to produce lead oxide, nitrogen dioxide and oxygen.

(iii) Nitrogen gas combines with hydrogen to form ammonia.

28. Name the three products obtained in chlor-alkali process mentioning the electrode where they are obtained in the instrument used. Write one important use of each product. 3

29. (a) What is a synapse? How is an electrical impulse created in a nerve cell and what is the role of synapse in this context?

(b) Name the source of secretion and one function each of the following animal hormones:

(i) Thyroxin

(ii) Insulin

(iii) Growth hormone

30. What are plant hormones? Where are they synthesised? What happens when a growing plant detects light? 3

31. An object of height 4.0 cm is placed at a distance of 30 cm from the optical centre of a convex lens of focal length 20 cm. Use lens formula to determine:

(i) the distance of the image from the optical centre and

(ii) height of the image formed. 3

32. (a) (i) List two important safety measures commonly used in domestic electric circuits and the appliances such as electric irons/ovens.

(ii) The power rating of an electric appliance is 220 V; 2 kW. If it is used in a room having electric circuit of current rating of 5 A, what result do you expect? Give reason for your answer with necessary calculations.

(b) Name and state the rule to determine the direction of a:

(i) magnetic field produced around a straight conductor carrying a steady current.

(ii) force experienced by a current carrying straight conductor placed perpendicular to a uniform magnetic field.

33. A gas 'G', which is deadly poisonous, is found at the higher levels of atmosphere and performs an essential function. Name the gas 'G' and state the function performed by this gas in the atmosphere. Name the chemicals linked to the decrease in the level of this gas. Write the measures which have been taken by an International Organisation to check the depletion of the layer of this gas at the higher levels of earth's atmosphere.

SECTION = D

34. (a) (i) Give reason why carbon can neither form C⁴⁺ cations nor C⁴⁻ anions but forms covalent compounds.

(ii) What is a homologous series of carbon compounds? Write the molecular formula of any two consecutive members of a homologous series of aldehydes.

(iii) Write the number of (1) single covalent bonds and (2) double covalent bonds in a molecule of benzene.

(b) (i) Write the name and the molecular formula of a commercially important carbon compound having functional group –OH.

(ii) Write chemical equations to show the reactions of the above mentioned compound with:

(1) excess conc. sulphuric acid

(2) ethanoic acid in the presence of an acid catalyst

(3) sodium metal

(4) alkaline potassium permanganate (KMnO₄)

Also write the name of the product formed in each of the above reactions.

35. (a) State in brief what happens when in a human female:

(i) an egg is not fertilised and

(ii) fertilisation takes place. 5

(b) List three techniques/devices used by human females to avoid pregnancy. Mention the side-effects caused by each method.

36. (a) Define Electric power. Express electric power of an electric appliance in terms of its resistance (R) and the voltage / potential difference (V) at which it operates. 5

(b) The rated voltage of an air-conditioner is 220 V. This air-conditioner consumes 22 units of electric energy in 10 hours. Calculate:

(i) Power rating of the air-conditioner,

(ii) Current drawn by the air-conditioner, and

(iii) Resistance of the air-conditioner.

SECTION = E

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

37. The metals produced by various reduction processes are not very pure. They contain impurities which must be removed to obtain pure metals. The most widely used process for refining impure metals is electrolytic refining. In this process chemical effect of electric current is used.

(a) Name the materials used to make anode and cathode in the refining of copper by this process.

(b) Name the salt of copper used as an electrolyte in this process and write its molecular formula.

(c) (i) What happens when a steady current is passed through the electrolyte? Name the part of the electrolytic cell where (1) pure copper is obtained and (2) impurities settle.

(ii) How is copper obtained from its sulphide? Write chemical equations involved in the process.

38. More than a century ago Gregor Johann Mendel worked out the main rules of heredity by working on the garden pea plants using a number of visible contrasting characters – round/wrinkled seeds, short/tall plants, violet/white flowers and so on. He conducted a number of experiments by making a cross with one or two pairs of contrasting characters of the pea plants. On the basis of his observations, Mendel made certain conclusions which helped him to arrive at the laws of inheritance.

(a) In a cross between violet flowered pea plants (VV) and white flowered pea plants (ww), state the characteristics of the plants obtained in F₁ progeny.

(b) If the plants of F₁ progeny obtained in (a) are self-pollinated, in what ratio would the plants with gene combinations (VV) and (Vw) be observed in the plants of F₂ progeny?

(c) (i) If 800 plants are produced in F₂ progeny of the above mentioned cross, how many plants will show the recessive character? Justify your answer.

(ii) Justify the statement "Sex of the children in human beings will be determined by the chromosome they inherit from their father."

39. The human eye is one of the most valuable and sensitive sense organs. Eyes enable us to see the wonderful world around us. We observe that some persons cannot see the objects distinctly and comfortably. The vision becomes blurred due to the refractive defects of the eye.

(a) When do we say that a person is suffering from myopia?

(b) List two main causes of myopia.

(c) (i) When do we say that a person is suffering from presbyopia? Write the structure of common type of bifocal lenses used by the persons suffering from presbyopia.

(ii) A person is using corrective lenses of power +0.25 D in his spectacles for seeing the objects clearly. Name the defect of vision he is suffering from. Also calculate the focal length of the lenses used in his spectacles.

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Class 10 Science Compartment Previuos Year Question and Answer 2025

Science , 2025

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

(II) 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.

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

(IV) Please write down the Serial Number of the question in the answer-book at the given place 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. From the following, select a process in which combination reaction occurs :

(A) Black and white photography

(B) Burning of carbon (coal)

(D) Refining of copper

2. Select exothermic processes from the following :

(i) Dilution of acid

(ii) Burning of natural gas

(iii) Evaporation of water

(iv) Electrolysis of water

(A) (i) and (ii)

(B) (ii) and (iii)

(D) (i) and (iv)

3. The most malleable metals are :

(A) Iron and gold

(B) Copper and silver

(D) Gold and copper

4. Consider the reactions of dil. hydrochloric acid with the following metals :

Aluminium, Copper, Iron, Magnesium and Zinc

The correct observation is :

(A) Most vigorous reaction with aluminium and no reaction with iron

(B) Most vigorous reaction with magnesium and no reaction with iron

(D) Most vigorous reaction with zinc and no reaction with copper

5. The number of covalent bond(s) present in a nitrogen molecule is/are :

(Atomic number of nitrogen is 7)

(A) 1 (B) 3 (C) 5 (D) 7

6. The valves in the human heart ensure that :

(i) Oxygen-rich blood flows from left atrium to left ventricle only.

(ii) Deoxygenated blood flows from left atrium to left ventricle only.

(iii) Oxygen-rich blood flows from right atrium to right ventricle only.

(iv) Deoxygenated blood flows from right atrium to right ventricle only.

(A) (i) and (iii)

(B) (ii) and (iv)

(D) (ii) and (iii)

7. The part of the hindbrain present immediately above the medulla is :

(A) Cerebellum (B) Pons (C) Cerebrum (D) Spinal cord

8. Application of Abscisic acid on plants promotes :

(A) Development of fruits

(B) Wilting of leaves

(D) Formation of flowers

9. The end product of meiosis in a reproductive cell in plants is :

(A) Zygote

(B) Pollen grains

(D) Egg

10. In garden pea, violet colour flower is the dominant trait over white colour flower which is the recessive trait. When parent plant with violet coloured flowers (Vv) is crossed with a parent plant with white flowers, the possible percentage of occurrence of traits in the progeny would be :

(A) 100% violet

(B) 50% violet, 50% white

(D) 75% violet, 25% white

11. A 5 cm long rod is placed vertically in front of a concave mirror. If its 5 cm long image is formed at 20 cm in front of the mirror, the focal length of the mirror is :

(A) − 20 cm (B) − 10 cm (C) − 5 cm (D) 20 cm

12. An optical device which always produces images of m = + 1 is :

(A) Plane mirror

(B) Convex mirror

(D) Convex lens

13. Which one of the following factors affects the electrical resistivity of a conductor ?

(A) Temperature

(B) Length

(D) Thickness

14. The strength of the magnetic field inside a current carrying long straight solenoid is :

(A) maximum at its centre.

(B) minimum at its centre.

(D) uniform throughout its length.

15. The organism occupying the fourth trophic level in a food chain operating in grassland is :

(A) Green plants

(B) Frog

(D) Snake

16. Which one of the following statements is incorrect about the effect on our environment as a result of our activities ?

(A) Improvement in our lifestyle has resulted in greater amounts of waste.

(B) Packaging of materials has resulted in lesser amount of non-biodegradable waste.

(D) Harmful wastes that are non-biodegradable persist in the environment for a long time.

(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) : Decomposition of vegetable matter into compost is an exothermic reaction.

Reason (R) : Decomposition reactions need energy to break down the reactants.

18. Assertion (A) : Transpirational pull helps in the absorption and upward movement of water and dissolved minerals in plants.

Reason (R) : The effect of root pressure in transport of water is more significant at night.

19. Assertion (A) : In our homes we receive supply of electric power through a main supply. One of the wires in this supply, usually with red insulation, is called live wire and another wire with green insulation is called neutral wire.

Reason (R) : In our country, the potential difference between the live wire and the neutral wire is 220 volts.

20. Assertion (A) : Due to scattering of sunlight, the clear sky predominantly appears blue.

Reason (R) : The wavelength of blue light is nearly 1.8 times the wavelength of red light.

SECTION = B

Questions no. 21 to 26 are Very Short Answer Type questions.

21. Translate the following statements into balanced chemical equations : 2

(a) Aluminium reacts with copper chloride to form aluminium chloride and copper.

(b) Zinc reacts with sodium hydroxide to give sodium zincate and hydrogen gas.

22. (a) (i) What is an alloy ?

(ii) Write the composition of solder and the property which makes it suitable for welding electric wires. 2

(b) During electrolytic refining of silver : 2

(i) What are the electrodes – cathode and anode made up of ?

(ii) What is anode mud ? Why is it called so ?

23. Give reasons : 2

(a) During a breathing cycle, the lungs always contain a residual volume of air.

(b) As compared to oxygen, carbon dioxide is mostly transported in dissolved form in our blood.

24. (a) Explain how tendrils help a pea plant climb up other plants or fences. 2

(b) List two major limitations of the use of electrical impulses as a means of communication between the cells in most multicellular animals. 2

25. An object is placed 25 cm in front of a concave mirror of focal length

15 cm. Use mirror formula and new cartesian sign convention to determine the position of the image formed. 2

26. Draw a ray diagram to show the path of a ray of light which falls obliquely on one of the faces of an equilateral triangular prism made of glass and mark on it the angle of incidence () and the angle of deviation (). 2

SECTION = C

Questions no. 27 to 33 are Short Answer Type questions.

27. (a) Write the name and chemical formula of a sodium compound which is sometimes added for faster cooking. How is it produced from sodium chloride as one of the raw materials ? Give chemical equation for the reaction involved.

(b) The compound mentioned in (a) above is also an ingredient of antacids. Why ? 2+1

28. Define a displacement reaction. Name a displacement reaction which is highly exothermic and has its use in joining railway tracks. Explain the process with a balanced chemical equation of the reaction that occurs. 3

29. (a) Write the end products of the breakdown of pyruvate in yeast cells and in our muscle cells under anaerobic conditions.

(b) In which part of the cell does the above process take place ? [2 1/2 + ½]

30. (a) Explain the process of translocation of food and other substances in the phloem of plants. 3

(b) Differentiate between xylem and phloem on the basis of the following : 3

(i) Direction of transport of the substances

(ii) Major driving forces involved in the transport

(iii) Nature of the substance(s) transported

31. Show the arrangement of three resistors of 2Ω , 3 Ω and 6 Ω which are connected in such a way that the total/equivalent resistance of the combination is (a) 1 Ω, and (b) 4 Ω . Justify your answer in each case. 3

32. As shown in the figure a small aluminum rod AB is suspended horizontally between the poles of a strong horseshoe magnet. This rod is also connected with a battery and a key. Study the arrangement shown.

Photo

(a) State Fleming’s left-hand rule.

(b) Apply Fleming’s left-hand rule to determine :

(i) What is observed when a current is passed from B to A in the rod ?

(ii) What is observed when a current is passed from A to B in the rod ?

(iii) What is observed when the rod AB is aligned parallel to the magnetic field and current is passed through it from B to A ? Justify your answer in this case. 1+2

33. (a) Define the term biological magnification.

(b) In the given aquatic food chain, which trophic level will have highest effect of biological magnification and why ? 1+2

Phytoplankton → Zooplankton → Fishes → Human

SECTION = D

Questions no. 34 to 36 are Long Answer Type questions.

34. (a) Name and state in brief the process used to obtain sodium hydroxide from brine. In this process, along with the main product (i.e., sodium hydroxide), two gases A and B are also produced at the two electrodes. Name A and B specifying the name of their respective electrodes. One of these gases, when reacting with dry calcium hydroxide, produces a compound C which is used as an oxidising agent in many chemical industries as well as to make drinking water free from germs. Name C and write the chemical equation for the reaction in its formation. 3+2

(b) When dry crystals of ferrous sulphate were heated in a dry boiling tube, some tiny water droplets were observed in the tube after some time. 5×1=5

(i) State the source of these water droplets.

(ii) Write the colour change observed during heating.

(iii) Write the balanced chemical equation of the reaction that occurs during heating.

(iv) How many water molecules are attached per formula unit of ferrous sulphate crystal ?

(v) Write the molecular formula of crystalline form of (I) copper sulphate, and (II) sodium carbonate.

35. (a) (i) Define the term power of accommodation of human eye. What happens to the image distance in the eyes when the distance of an object is increased gradually from about 5 m to 500 m from our eyes ? Name and explain the role of the part of human eye responsible for it in this case.

(ii) A person is unable to see distinctly the objects placed beyond 2 m from his eyes. Name the defect of vision the person is suffering from. List two possible causes of this defect and write the type of lenses used for the correction of this defect. 3+2

(b) (i) Name and explain the phenomenon of light responsible to make the path of a beam of light visible when it enters a smoke/dust-filled room through a small hole. Also state the dependence of the colour of the light we receive on the size of the particles of the medium through which the light passes.

(ii) A person suffering from presbyopia needs spectacles having bifocal lenses. If the power of two lenses used in his spectacles is + 2·0 D and − 0·5 D, which one of the two lenses is for the correction of his distant vision and what is its focal length ? 3+2

36. (a) (i) In which form is the information for inheritance of features transmitted from one generation to the next generation ?

(ii) Differentiate between binary fission in Amoeba and Leishmania.

(iii) “Fragmentation cannot be a method of reproduction in all multicellular organisms.” Justify this statement. 1+2+2

(b) (i) Define placenta. State the structure and role of placenta in the development of embryo in human beings.

(ii) List three categories of contraceptives and give one example of each. 2+3

SECTION = E

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

37. All compounds of carbon which contain only carbon and hydrogen are called hydrocarbons. Among these, saturated hydrocarbons are called ‘alkanes’, unsaturated compounds with one or more double bonds are called ‘alkenes’ and compounds containing one or more triple bonds are called ‘alkynes’.

(a) Identify the following compound and write its name. 1

(b) How do saturated and unsaturated carbon compounds differ in terms of the flame produced by them on burning ? 1

38. The process of determining the sex of a newborn is purely genetic. But still many people in some societies believe that only the woman (mother) is responsible for determination of the sex of the child and blame her. In fact, the sex of the child is genetically determined. But there are some animals where sex is not genetically determined.

(a) Define sex chromosomes. 1

(b) Mention one example of animals where sex is not genetically determined. How is sex determined in these animals ? Explain. 1

(c) (i) Does the genetic combination of the mother play a significant role in determining the sex of newborn ? Explain. 2

39. In a domestic circuit, six LED bulbs and a ceiling fan are arranged as per the circuit shown in the figure. The source voltage is 220 volts and the power rating of each device is marked in the circuit diagram. Two fuses F1 and F 2 are also provided in the circuit. Based on the circuit diagram, answer the following questions :

Photo

(a) State what happens when 1

(i) only key K 1 is closed,

(ii) and key K 2 is also closed .

(b) Find the current drawn by the bulb L. 1

(c) (i) Calculate the resistance of the bulb A. Find the total resistance offered by the circuit to the flow of current when only key K2 is closed. 2

(c) (ii) What would happen to the glow of the bulbs in the circuit when K1 and K2 both are closed and the fuse F1 melts suddenly ? Give reason to justify your answer. 2

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Class 10 Science Compartment Previous Year Question and Answer 2025

(FOR VISUALLY IMPAIRED CANDIDATES ONLY)

Science , 2025

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

(II) 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.

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

(IV) Please write down the Serial Number of the question in the answer-book at the given place before attempting it.

Time allowed : 3 hours Maximum Marks : 80