CBSE Class 10th Science Compartment Exam Question Paper Answer Key 2025, Download PDF

CBSE Class 10 Compartment Exam Science Answer Key 2025: The CBSE Class 10 Science Compartment Board Exam 2025 took place on 18 July 2025. According to initial student reactions, the paper was moderately difficult. To help the students assess their performance, we have provided the CBSE Class 10 Science Compartment Exam Answer Key 2025 in this article. Subject experts prepared the answer key, which serves as an essential resource for students to verify their answers and estimate their scores. By using the answer key, students can learn from their mistakes and enhance their preparation for future exams.

Also, check: CBSE Class 10th, 12th Syllabus 2025-26

CBSE Class 10 Science Exam 2025: Highlights

The CBSE Class 10Science question paper is of 80 marks. The time allowed to write the paper was 3 hours. All questions were compulsory, with some questions having internal choices.

Features Of CBSE Class 10th Science Answer Key?

1. Self-Evaluation:

Students can compare their answers with the official solutions to understand their performance.

2. Score Estimation:

By checking the answer key, students can predict their approximate marks before the official results are announced.

3. Identify Mistakes:

Analysing incorrect answers helps students understand their weak areas for improvement in future exams.

CBSE Class 10 Science Marking Scheme 2025

Check the CBSE 10th Science Marking Scheme 2025 in the table below. 

CBSE Class 10 Compartment Exam Science Question Paper 2025

Check the question paper below and download the PDF for free. 

CBSE Class 10 Compartment Exam Science Answer Key 2025

Get here the complete answer key for CBSE Class 10th Science Exam 2025

1.Question: From the following, select a process in which combination reaction occurs:

(A) Black and white photography

(B) Burning of carbon (coal)

(C) Burning of methane

(D) Refining of copper

Answer: (B) Burning of carbon (coal)

2.Question: 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)

(C) (iii) and (iv)

(D) (i) and (iv)

Answer: (A) (i) and (ii)

3.Question: The most malleable metals are:

(A) Iron and gold

(B) Copper and silver

(C) Silver and gold

(D) Gold and copper

Answer: (D) Gold and copper

4.Question: Consider the reactions of dilute 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

(C) Most vigorous reaction with magnesium and no reaction with copper

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

Answer: (C) Most vigorous reaction with magnesium and no reaction with copper

5.Question: 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

Answer: (B) 3

6.Question: 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)

(C) (i) and (iv)

(D) (ii) and (iii)

Answer: (C) (i) and (iv)

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

(A) Cerebellum

(B) Pons

(C) Cerebrum

(D) Spinal cord

Answer: (B) Pons

8.Question: Application of Abscisic acid on plants promotes:

(A) Development of fruits

(B) Wilting of leaves

(C) Elongation of stem

(D) Formation of flowers

Answer: (B) Wilting of leaves

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

(A) Zygote

(B) Pollen grains

(C) Sperms

(D) Egg

Answer: (B) Pollen grains

10.Question: 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 F1 progeny would be:

(A) 100% violet

(B) 50% violet, 50% white

(C) 25% violet, 75% white

(D) 75% violet, 25% white

Answer: (B) 50% violet, 50% white

11.Question: 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

Answer: (B) −10 cm

(Since the image is same size and real, magnification = −1, thus object distance = −20 cm, using mirror formula gives f = −10 cm)

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

(A) Plane mirror

(B) Convex mirror

(C) Concave mirror

(D) Convex lens

Answer: (A) Plane mirror

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

(A) Temperature

(B) Length

(C) Shape

(D) Thickness

Answer: (A) Temperature

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

(A) Maximum at its centre.

(B) Minimum at its centre.

(C) Maximum at the ends and minimum at its centre.

(D) Uniform throughout its length.

Answer: (D) Uniform throughout its length.

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

(A) Green plants

(B) Frog

(C) Grasshopper

(D) Snake

Answer: (D) Snake

(Trophic levels: 1st–Green plants → 2nd–Grasshopper → 3rd–Frog → 4th–Snake)

16.Question: 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.

(C) Use of disposable cups/kulhads results in loss of fertile topsoil.

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

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

(This is incorrect – packaging often increases non-biodegradable waste.)

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

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

Options:

(A) Both A and R are true, and R is the correct explanation of A

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

(C) A is true, but R is false

(D) A is false, but R is true

Answer: (C) A is true, but R is false

(Decomposition of vegetable matter releases heat, but not all decomposition requires energy input.)

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.

Answer: (B) Both A and R are true, but R is not the correct explanation of A

(Transpiration pull is the major force, not root pressure.)

19.Assertion (A): In our homes we receive supply of electric power through a main supply. One of the wires in the supply is live wire and the other is neutral wire.

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

Answer: (A) Both A and R are true, and R is the correct explanation of A

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.

Answer: (C) A is true, but R is false

(The actual wavelength of blue light is shorter, but not exactly 1/8th of red.)

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