Class 10th CBSE Science Top 50 Questions With Answer PDF

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CBSE Science Top 50 MCQ Quiz

1. What is the unit of inheritance?

a) DNA b) Gene c) Chromosome d) Nucleus

Answer: b) Gene

2. Which is the powerhouse of the cell?

a) Nucleus b) Mitochondria c) Ribosome d) Golgi apparatus

Answer: b) Mitochondria

3. The site of photosynthesis in plant cells is:

a) Mitochondria b) Chloroplast c) Ribosome d) Nucleus

Answer: b) Chloroplast

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

a) Hydrogenation b) Saponification c) Fermentation d) Hydrolysis

Answer: a) Hydrogenation

5. The mirror used in car side mirrors is:

a) Plane mirror b) Concave mirror c) Convex mirror d) Cylindrical mirror

Answer: c) Convex mirror

6. The main excretory product in humans is:

a) Ammonia b) Urea c) Uric acid d) Carbon dioxide

Answer: b) Urea

7. What is the focal length of a convex lens?

a) Positive b) Negative c) Zero d) Infinity

Answer: a) Positive

8. What is the molecular formula of methane?

a) CH3 b) CH4 c) C2H6 d) C3H8

Answer: b) CH4

9. Which gas is evolved when metals react with acids?

a) Oxygen b) Hydrogen c) Nitrogen d) Carbon dioxide

Answer: b) Hydrogen

10. 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

11. What type of bond is formed between two atoms sharing electrons?

a) Ionic bond b) Covalent bond c) Metallic bond d) Hydrogen bond

Answer: b) Covalent bond

12. Water boils at what temperature in Celsius?

a) 50°C b) 75°C c) 100°C d) 150°C

Answer: c) 100°C

13. Which planet has the highest gravity in the solar system?

a) Earth b) Saturn c) Jupiter d) Mars

Answer: c) Jupiter

14. The basic unit of life is:

a) Atom b) Molecule c) Cell d) Organ

Answer: c) Cell

15. The chemical formula of common salt is:

a) NaCl b) KCl c) Na2SO4 d) CaCl2

Answer: a) NaCl

16. The speed of light in vacuum is approximately:

a) 3 x 10^6 m/s b) 3 x 10^7 m/s c) 3 x 10^8 m/s d) 3 x 10^9 m/s

Answer: c) 3 x 10^8 m/s

17. What is the function of red blood cells?

a) Fight infection b) Carry oxygen c) Clot blood d) Digest food

Answer: b) Carry oxygen

18. Which gas is essential for respiration in humans?

a) Carbon dioxide b) Oxygen c) Nitrogen d) Hydrogen

Answer: b) Oxygen

19. The contact force that opposes motion between two surfaces is called:

a) Tension b) Friction c) Gravity d) Magnetic force

Answer: b) Friction

20. The pH of pure water is:

a) 7 b) 0 c) 14 d) 1

Answer: a) 7

21. Which vitamin is produced by the skin on exposure to sunlight?

a) Vitamin A b) Vitamin B c) Vitamin C d) Vitamin D

Answer: d) Vitamin D

22. The metal which is liquid at room temperature:

a) Iron b) Mercury c) Aluminum d) Copper

Answer: b) Mercury

23. The SI unit of electric current is:

a) Volt b) Ampere c) Watt d) Ohm

Answer: b) Ampere

24. Which organ in humans produces insulin?

a) Liver b) Pancreas c) Kidney d) Spleen

Answer: b) Pancreas

25. The chemical used to disinfect water is:

a) Salt b) Bleach c) Chlorine d) Sugar

Answer: c) Chlorine

26. Which part of the plant transports water?

a) Phloem b) Xylem c) Stomata d) Root hair

Answer: b) Xylem

27. What is the chemical name of baking soda?

a) Sodium chloride b) Sodium bicarbonate c) Calcium carbonate d) Potassium chloride

Answer: b) Sodium bicarbonate

28. The nerve cell is called:

a) Neuron b) Axon c) Dendrite d) Synapse

Answer: a) Neuron

29. The force which keeps planets in orbit around the sun is:

a) Magnetic force b) Gravitational force c) Electric force d) Frictional force

Answer: b) Gravitational force

30. The hardest natural substance on earth is:

a) Gold b) Diamond c) Quartz d) Graphite

Answer: b) Diamond

31. Which vitamin is necessary for blood clotting?

a) Vitamin K b) Vitamin E c) Vitamin A d) Vitamin B12

Answer: a) Vitamin K

32. The process by which plants lose water vapor is called:

a) Transpiration b) Respiration c) Photosynthesis d) Germination

Answer: a) Transpiration

33. Acid rain is caused by excess presence of:

a) Carbon dioxide b) Sulfur dioxide c) Oxygen d) Nitrogen

Answer: b) Sulfur dioxide

34. The function of white blood cells is:

a) Transport oxygen b) Fight infection c) Clot blood d) Digest food

Answer: b) Fight infection

35. Which of the following is a non-renewable energy source?

a) Solar energy b) Wind energy c) Natural gas d) Hydropower

Answer: c) Natural gas

36. Where does Benedict’s test turn positive?

a) Protein b) Sugar c) Fats d) Starch

Answer: b) Sugar

37. The chemical symbol for Iron is:

a) Ir b) Fe c) I d) In

Answer: b) Fe

38. The SI unit of force is:

a) Joule b) Newton c) Pascal d) Watt

Answer: b) Newton

39. What gas do plants take in for photosynthesis?

a) Oxygen b) Carbon dioxide c) Nitrogen d) Hydrogen

Answer: b) Carbon dioxide

40. The boiling point of water decreases with:

a) Increase in pressure b) Decrease in pressure c) Increase in temperature d) Decrease in temperature

Answer: b) Decrease in pressure

41. Which element is found in all organic compounds?

a) Oxygen b) Nitrogen c) Carbon d) Hydrogen

Answer: c) Carbon

42. The process of breaking down food to release energy is called:

a) Photosynthesis b) Respiration c) Digestion d) Excretion

Answer: b) Respiration

43. The SI unit of frequency is:

a) Hertz b) Decibel c) Newton d) Joule

Answer: a) Hertz

44. The atomic number of carbon is:

a) 12 b) 14 c) 6 d) 8

Answer: c) 6

45. Which part of the brain controls voluntary actions?

a) Cerebrum b) Cerebellum c) Medulla d) Spinal cord

Answer: a) Cerebrum

46. The boiling point of water at sea level is:

a) 90°C b) 100°C c) 110°C d) 120°C

Answer: b) 100°C

47. The element with atomic number 1 is:

a) Helium b) Oxygen c) Hydrogen d) Nitrogen

Answer: c) Hydrogen

48. The number of chromosomes in a human body cell is:

a) 46 b) 23 c) 44 d) 22

Answer: a) 46

49. Which gas is used in electric bulbs to prevent filament oxidation?

a) Nitrogen b) Oxygen c) Argon d) Carbon dioxide

Answer: c) Argon

50. The process of cell division in body cells is called:

a) Meiosis b) Mitosis c) Fertilization d) Pollination

Answer: b) Mitosis

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