Most Important Science Objective Questions with Answers for CDS Examination in September 25

Most Important Science Objective Questions with Answers for CDS Examination in September 25

Science Objective Questions with Answers

1. Which vitamin is produced in the body by sunlight?

          Vitamin D – Synthesized in skin when exposed to UVB rays

2. The chemical formula of baking soda is?

          NaHCO₃ – Sodium bicarbonate, used in baking and cleaning.

3. Which gas is known as “Laughing Gas”?

          Nitrous oxide (N₂O) – Causes mild euphoria, used in anesthesia.

4. Who discovered the electron?

J.J. Thomson – Identified the electron in 1897

5. Which organ purifies blood in the human body?

          Kidneys – Filter waste from blood and regulate fluid balance.

6. The SI unit of force is?

Newton (N) – Defined as kg·m/s².

7. Which law explains the relationship between current, voltage, and resistance?

          Ohm’s Law – V = IR (Voltage = Current × Resistance).

8. Name the process by which plants lose water through stomata.

Transpiration – Occurs through stomata in leaves..

9. Which part of the cell is known as the “powerhouse”?

          Mitochondria – Generate ATP, the cell’s energy currency

10. Which layer of atmosphere contains the ozone layer?

          Stratosphere – Protects Earth from harmful UV rays

11. Which metal is liquid at room temperature?

          Mercury (Hg) – Only metal liquid at room temperature.

12. The speed of light is approximately?

~300,000 km/s – Precisely 299,792,458 m/s in vacuum.

13. Who proposed the theory of evolution by natural selection?

          Charles Darwin – Proposed natural selection in 1859.

14. Which acid is found in lemon?

Citric acid – Gives lemon its sour taste

15. The element essential for photosynthesis is?

          Magnesium – Central atom in chlorophyll

16. DNA stands for?

Deoxyribonucleic Acid – Carries genetic instructions.

17. The hardest substance in the human body is?

          Tooth enamel – Harder than bone, protects teeth

18. Which blood group is called the “Universal Donor”?

O negative (O−) – Can donate to all blood types.

19. Sound cannot travel through?

          Vacuum – Sound needs particles to travel.

20. Which part of the human brain controls balance?

Cerebellum – Coordinates movement and balance

21. The chemical name of common salt is?

          Sodium chloride (NaCl) – Used in food and industry

22. The ozone layer protects us from which rays?

Ultraviolet (UV) rays – Especially UV-B and UV-C.

23. Who discovered penicillin?

          Alexander Fleming – Found it in 1928 from mold

24. The boiling point of water is?

100°C (212°F) – At standard atmospheric pressure

25. The first artificial satellite of the world was?

          Sputnik 1 – Launched by USSR in 1957.

26. Who invented the telephone?

Alexander Graham Bell – Patented in 1876

27. The process of conversion of milk into curd is due to?

          Lactic acid bacteria – Ferment lactose into lactic acid

28. Which device is used to measure blood pressure?

          Sphygmomanometer – Measures blood pressure

29. Which part of the plant conducts food?

Phloem – Transports sugars from leaves

30. Kyoto Protocol is related to?

          Climate change – International treaty to reduce emissions.

31. Which is the smallest bone in the human body?

Stapes – Found in the middle ear

32. The human body has how many pairs of ribs?

          12 pairs – Protect thoracic organs

33. Which gas is used in fire extinguishers?

Carbon dioxide (CO₂) – Smothers fire by displacing oxygen

34. The most abundant element in the Earth’s crust is?

          Oxygen – Makes up ~46% of Earth’s crust

35. Which organ in the human body secretes insulin?

          Pancreas – Regulates blood sugar

36. Who discovered the X-rays?

          Wilhelm Röntgen – Discovered in 1895

37. The unit of energy is?

Joule (J) – SI unit of energy

38. Which device converts chemical energy into electrical energy?

          Battery – Converts stored chemical energy to electricity

39. Photosynthesis occurs in which part of plant cells?

Chloroplasts – Contain chlorophyll for light absorption

40. Which blood cells help in clotting of blood?

          Platelets – Help form clots to stop bleeding.

41. The blue colour of the sky is due to?

          Rayleigh scattering – Short blue wavelengths scatter more.

42. Which is the largest gland in the human body?

          Liver – Performs detoxification and metabolism.

43. The SI unit of temperature is?

          Kelvin (K) – SI unit; starts from absolute zero.

44. The Richter scale is used to measure?

          Earthquake magnitude – Measures seismic energy

45. Which metal is used in galvanisation?

          Zinc – Prevents rusting of iron

46. The study of fungi is called?

          Mycology – Branch of biology.

47. Which is the cleanest form of energy?

          Solar energy – Renewable and non-polluting.

48. The substance used in pencils is?

          Graphite – A form of carbon

49. The gas responsible for acid rain is?

          Sulfur dioxide (SO₂) – Combines with water to form acid.

50. Which vitamin deficiency causes scurvy?

          Vitamin C – Deficiency causes bleeding gums and fatigue.

51. Which vitamin is produced in the skin by sunlight?

          Vitamin D – Produced in skin via UVB exposure.

52. Which gas is used in fire extinguishers?

          Carbon dioxide (CO₂) – Non-flammable and displaces oxygen

53. What is the SI unit of force?

          Newton (N)

54. Which organ controls blood sugar levels?

          Pancreas – Secretes insulin and glucagon

55. Which part of the cell contains genetic material?

          Nucleus – Contains DNA in chromosomes

These are science objective questions with answers from the article posted previously , advised to test your self