CBSE Class 10 Science Exam 2025 : Top 50 MCQs with Answers for Quick Revision (February 20)

1. What type of reaction is represented by the following equation? 2Mg + O2 → 2MgO

(a) Combination Reaction

(b) Decomposition Reaction

(c) Displacement Reaction

(d) Redox Reaction

Answer: (a) Combination Reaction 

2. Which of the following is an example of a double displacement reaction?

(a) NaCl + AgNO3 → AgCl + NaNO3

(b) 2H2 + O2 → 2H2O

(c) Zn + HCl → ZnCl2 + H2

(d) CaCO3 → CaO + CO2

Answer: (a) NaCl + AgNO₃ → AgCl + NaNO₃ (Double Displacement Reaction)

3. What is the pH of pure water?

(a) 5

(b) 7

(c) 9

(d) 11

Answer: (b) 7 (pH of pure water)

4. Which of the following is a strong acid?

(a) Acetic acid

(b) Citric acid

(c) Hydrochloric acid

(d) Carbonic acid

Answer: (c) Hydrochloric acid (Strong acid)

5. Which metal is the best conductor of electricity?

(a) Iron

(b) Copper

(c) Silver

(d) Aluminium

Answer: (c) Silver (Best conductor of electricity)

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6. What is the nature of oxides of non-metals?

(a) Basic

(b) Acidic

(c) Neutral

(d) Amphoteric

Answer: (b) Acidic (Nature of oxides of non-metals)

7. The general formula of alkane is:

(a) CnH2n

(b) CnH2n+2

(c) CnH2n-2

(d) CnH2n+1

Answer: (b) CₙH₂ₙ₊₂ (General formula of alkane)

8. The functional group present in aldehyde is: 

(a) -OH

(b) -COOH

(c) -CHO

(d) -CO

Answer: (c) -CHO (Functional group of aldehyde)

9. Which part of the plant is responsible for photosynthesis?

(a) Root

(b) Stem

(c) Leaf

(d) Flower

Answer: (c) Leaf (Responsible for photosynthesis)

10. In human digestion, which enzyme breaks down starch?

(a) Pepsin

(b) Trypsin

(c) Amylase

(d) Lipase

Answer: (c) Amylase (Breaks down starch)

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11. Which hormone regulates blood sugar levels?

(a) Thyroxine

(b) Insulin

(c) Adrenaline

(d) Estrogen

Answer: (b) Insulin (Regulates blood sugar levels)

12. What is the functional unit of the nervous system?

(a) Nephron

(b) Neuron

(c) Alveoli

(d) Axon

Answer: (b) Neuron (Functional unit of the nervous system)

13. What is the mode of reproduction in bacteria?

(a) Budding

(b) Binary fission

(c) Fragmentation

(d) Sporulation

Answer: (b) Binary fission (Mode of reproduction in bacteria)

14. Which of the following is an example of asexual reproduction?

(a) Fertilization

(b) Pollination

(c) Budding in yeast

(d) Zygote formation

Answer: (c) Budding in yeast (Example of asexual reproduction)

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15. The scientist who proposed the laws of inheritance is:

(a) Darwin

(b) Lamarck

(c) Mendel

(d) Pasteur

Answer: (c) Mendel (Proposed laws of inheritance)

16. What is the unit of inheritance?

(a) DNA

(b) Gene

(c) Chromosome

(d) Nucleus

Answer: (b) Gene (Unit of inheritance)

17. The focal length of a convex lens is:

(a) Positive

(b) Negative

(c) Zero

(d) Infinity

Answer: (a) Positive (Focal length of a convex lens)

18. The mirror used in car side mirrors is:

(a) Plane mirror

(b) Concave mirror

(c) Convex mirror

(d) Cylindrical mirror

Answer: (c) Convex mirror (Used in car side mirrors)

19. What is the cause of dispersion of light?

(a) Reflection

(b) Refraction

(c) Scattering

(d) Diffraction

Answer: (b) Refraction (Cause of dispersion of light)

20. The part of the human eye that controls the amount of light entering is:

(a) Retina

(b) Lens

(c) Iris

(d) Optic nerve

Answer: (c) Iris (Controls the amount of light entering the eye)

21. What type of reaction occurs when iron reacts with oxygen to form rust?

(a) Combination Reaction

(b) Decomposition Reaction

(c) Displacement Reaction

(d) Redox Reaction

Answer: (a) Combination Reaction

22. Which of the following is an example of a displacement reaction?

(a) Zn + CuSO4 → ZnSO4 + Cu

(b) 2Mg + O2 → 2MgO

(c) CaCO3 → CaO + CO2

(d) NaOH + HCl → NaCl + H2O

Answer: (a) Zn + CuSO4 → ZnSO4 + Cu

23. The process of breaking down a compound into simpler substances using heat is called:

(a) Combination Reaction

(b) Displacement Reaction

(c) Decomposition Reaction

(d) Neutralization Reaction

Answer: (c) Decomposition Reaction

24. What is the pH of a neutral solution?

(a) 1

(b) 7

(c) 14

(d) 0

Answer: (b) 7

25. Which gas is released when an acid reacts with a metal?

(a) Oxygen

(b) Nitrogen

(c) Hydrogen

(d) Carbon dioxide

Answer: (c) Hydrogen

26. Which of the following acids is present in vinegar?

(a) Hydrochloric acid

(b) Acetic acid

(c) Nitric acid

(d) Sulfuric acid

Answer: (b) Acetic acid

27. Which non-metal is a good conductor of electricity?

(a) Sulfur

(b) Phosphorus

(c) Graphite

(d) Iodine

Answer: (c) Graphite

28. The metal that does not react with dilute hydrochloric acid is:

(a) Zinc

(b) Copper

(c) Magnesium

(d) Iron

Answer: (b) Copper

29. Which process is used for the prevention of rusting?

(a) Galvanization

(b) Fermentation

(c) Sublimation

(d) Filtration

Answer: (a) Galvanization

30. What is the molecular formula of methane?

(a) CH3

(b) CH4

(c) C2H6

(d) C3H8

Answer: (b) CH4

31. The functional group present in alcohols is:

(a) -OH

(b) -COOH

(c) -CHO

(d) -COO-

Answer: (a) -OH

32. The process of converting vegetable oil into solid fat is called:

(a) Hydrogenation

(b) Saponification

(c) Fermentation

(d) Hydrolysis

Answer: (a) Hydrogenation

33. Which organelle is known as the powerhouse of the cell?

(a) Nucleus

(b) Mitochondria

(c) Ribosome

(d) Golgi apparatus

Answer: (b) Mitochondria

34. The site of photosynthesis in plant cells is:

(a) Mitochondria

(b) Chloroplast

(c) Ribosome

(d) Nucleus

Answer: (b) Chloroplast

35. What is the main excretory product in humans?

(a) Ammonia

(b) Urea

(c) Uric acid

(d) Carbon dioxide

Answer: (b) Urea

36. The hormone responsible for growth in plants is:

(a) Cytokinin

(b) Auxin

(c) Gibberellin

(d) Abscisic acid

Answer: (b) Auxin

37. Which part of the brain controls voluntary actions?

(a) Medulla

(b) Cerebellum

(c) Cerebrum

(d) Hypothalamus

Answer: (c) Cerebrum

38. Reflex actions are controlled by:

(a) Brain

(b) Spinal cord

(c) Heart

(d) Lungs

Answer: (b) Spinal cord

39. The mode of reproduction in amoeba is:

(a) Budding

(b) Binary fission

(c) Fragmentation

(d) Vegetative propagation

Answer: (b) Binary fission

40. Which hormone controls the menstrual cycle in females?

(a) Testosterone

(b) Estrogen

(c) Insulin

(d) Thyroxine

Answer: (b) Estrogen

41. Who is known as the father of genetics?

(a) Charles Darwin

(b) Gregor Mendel

(c) Louis Pasteur

(d) Watson and Crick

Answer: (b) Gregor Mendel

42. Which of the following is an example of a dominant trait in humans?

(a) Blue eyes

(b) Attached earlobes

(c) Curly hair

(d) Straight hair

Answer: (c) Curly hair

43. The mirror used in headlights of vehicles is:

(a) Concave mirror

(b) Convex mirror

(c) Plane mirror

(d) Cylindrical mirror

Answer: (a) Concave mirror

44. Which lens is used to correct myopia?

(a) Convex lens

(b) Concave lens

(c) Bifocal lens

(d) Cylindrical lens

Answer: (b) Concave lens

45. The resultant magnetic field at point 'P' situated midway between two parallel wires (placed horizontally) each carrying a steady current I is

(a) in the same direction as the current in the wires.

(b) in the vertically upward direction.

(c) zero

(d) in the vertically downward direction.

Answer: (c) zero

46. Consider the following statements:

(i) The sex of a child is determined by what it inherits from the mother.

(ii) The sex of a child is determined by what it inherits from the father.

(iii) The probability of having a male child is more than that of a female child.

(iv) The sex of a child is determined at the time of fertilisation when male and female gametes fuse to form a zygote.

The correct statements are:

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (iii) and (iv)

(d) (i), (iii) and (iv)

Answer: (b) (ii) and (iv)

47. Which one of the following organs is NOT a part of the human female reproductive system?

(a) Ovary

(b) Uterus

(c) Vas deferens

(d) Fallopian tube

Answer: (c) Vas deferens

48. The unit of refractive index is:

(a) No unit

(b) Meter

(c) Hertz

(d) Joule

Answer: (a) No unit

49. In which of the following organisms, multiple fission is a means of asexual reproduction?

(a) Yeast

(b) Leishmania

(c) Paramoecium

(d) Plasmodium

Answer: (d) Plasmodium

50. In bifocal lenses used for the correction of presbyopia:

(a) the upper portion is of convex lens for near vision and the lower part is a concave lens for distant vision.

(b) the upper portion is of convex lens for distant vision and the lower part is a concave lens for near vision.

(c) the upper portion is a concave lens for near vision and the lower part is of convex lens for distant vision.

(d) the upper portion is of the concave lens for the distant vision and the lower part is of the convex lens for the near vision.

Answer: (d) the upper portion is of the concave lens for the distant vision and the lower part is of the convex lens for the near vision.

51. Identify the food chain in which the organisms of the second trophic level are missing:

(a) Grass, goat, lion

(b) Zooplankton, Phytoplankton, small fish, large fish

(c) Tiger, grass, snake, frog

(d) Grasshopper, grass, snake, frog, eagle

(e) Tiger, grass, snake, frog

Answer: (e) Tiger, grass, snake, frog