Hard Level : Science MCQ Practice Set - 1
Q21. The largest organ in the human body is: āĻŽāĻžāĻ¨ā§ą āĻĻā§āĻšā§° āĻāĻāĻžāĻāĻ¤āĻā§ āĻĄāĻžāĻā§° āĻ āĻāĻ āĻā§āĻ¨āĻā§ ?
A. Brain | B. Skin | C. Liver | D. Heart
Ans: B. Skin
Explanation: Skin is the largest organ of the human body and protects the body from external damage. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻāĻžāĻŽāĻĄāĻŧāĻž āĻŽāĻžāĻ¨ā§ą āĻĻā§āĻšā§° āĻāĻāĻžāĻāĻ¤āĻā§ āĻĄāĻžāĻā§° āĻ āĻāĻ āĻā§°ā§ āĻ āĻŦāĻžāĻšāĻŋā§°ā§° āĻā§āĻˇāĻ¤āĻŋā§° āĻĒā§°āĻž āĻĻā§āĻšāĻ āĻ¸ā§ā§°āĻā§āĻˇāĻž āĻĻāĻŋāĻ¯āĻŧā§āĨ¤
Q22. The chemical formula of common salt is: āĻ¸āĻžāĻ§āĻžā§°āĻŖ āĻ¨ā§āĻ¨ā§° ā§°āĻžāĻ¸āĻžāĻ¯āĻŧāĻ¨āĻŋāĻ āĻ¸āĻāĻā§āĻ¤ āĻāĻŋ ?
A. NaCl | B. KCl | C. CaClâ | D. NaâCOâ
Ans: A. NaCl
Explanation: Common salt is sodium chloride (NaCl). āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻ¸āĻžāĻ§āĻžā§°āĻŖ āĻ¨ā§āĻ¨ āĻšā§āĻā§ Sodium Chloride (NaCl)āĨ¤
Q23. Which gas is required for respiration ? āĻļā§āĻŦāĻžāĻ¸-āĻĒā§ā§°āĻļā§āĻŦāĻžāĻ¸ā§° āĻŦāĻžāĻŦā§ āĻā§āĻ¨ āĻā§āĻ āĻĒā§ā§°āĻ¯āĻŧā§āĻāĻ¨ ?
A. Nitrogen | B. Oxygen | C. Carbon dioxide | D. Hydrogen
Ans: B. Oxygen
Explanation: Oxygen helps release energy from food during respiration. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻ āĻā§āĻ¸āĻŋāĻā§āĻ¨ā§ āĻļā§āĻŦāĻžāĻ¸-āĻĒā§ā§°āĻļā§āĻŦāĻžāĻ¸ āĻĒā§ā§°āĻā§ā§°āĻŋāĻ¯āĻŧāĻžāĻ¤ āĻāĻžāĻĻā§āĻ¯ā§° āĻĒā§°āĻž āĻļāĻā§āĻ¤āĻŋ āĻŽā§āĻā§āĻ¤ āĻā§°ā§āĨ¤
Q24. The hardest natural substance is: āĻĒā§ā§°āĻžāĻā§āĻ¤āĻŋāĻāĻāĻžā§ąā§ āĻāĻāĻžāĻāĻ¤āĻā§ āĻāĻ āĻŋāĻ¨ āĻĒāĻĻāĻžā§°ā§āĻĨ āĻā§āĻ¨āĻā§ ?
A. Gold | B. Diamond | C. Iron | D. Quartz
Ans: B. Diamond
Explanation: Diamond has the strongest crystal structure among natural substances. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻĄāĻžāĻ¯āĻŧāĻŽāĻŖā§āĻĄā§° āĻ¸ā§āĻĢāĻāĻŋāĻ āĻāĻ āĻ¨ āĻ āĻ¤ā§āĻ¯āĻ¨ā§āĻ¤ āĻŽāĻāĻŦā§āĻ¤ āĻšāĻāĻ¯āĻŧāĻžā§° āĻŦāĻžāĻŦā§ āĻ āĻĒā§ā§°āĻžāĻā§āĻ¤āĻŋāĻāĻāĻžā§ąā§ āĻāĻāĻžāĻāĻ¤āĻā§ āĻāĻ āĻŋāĻ¨ āĻĒāĻĻāĻžā§°ā§āĻĨāĨ¤
Q25. The unit of power is: āĻļāĻā§āĻ¤āĻŋā§° āĻšāĻžā§°ā§° āĻāĻāĻ āĻāĻŋ ?
A. Joule | B. Watt | C. Newton | D. Pascal
Ans: B. Watt
Explanation: Power is the rate of doing work and its SI unit is Watt. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Power āĻšā§āĻā§ āĻā§°ā§āĻŽ āĻā§°āĻžā§° āĻšāĻžā§° āĻā§°ā§ āĻāĻ¯āĻŧāĻžā§° SI āĻāĻāĻ WattāĨ¤
Q26. Which organ purifies blood in the human body ? :: āĻŽāĻžāĻ¨ā§ą āĻļā§°ā§ā§°āĻ¤ āĻā§āĻ¨ āĻ āĻāĻāĻ ā§°āĻā§āĻ¤ āĻļā§āĻĻā§āĻ§ āĻā§°ā§ ?
A. Heart | B. Liver | C. Kidney | D. Lungs
Ans: C. Kidney
Explanation: Kidneys filter waste materials and excess water from blood. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Kidney āĻ ā§°āĻā§āĻ¤ā§° āĻĒā§°āĻž āĻŦāĻ°ā§āĻā§āĻ¯ āĻĒāĻĻāĻžā§°ā§āĻĨ āĻā§°ā§ āĻ āĻ¤āĻŋāĻ°āĻŋāĻā§āĻ¤ āĻĒāĻžāĻ¨ā§ āĻĢāĻŋāĻ˛ā§āĻāĻžā§° āĻā§°ā§āĨ¤
Q27. Which part of the eye controls the amount of light entering ? :: āĻāĻā§āĻ¤ āĻĒā§ā§°ā§ąā§āĻļ āĻā§°āĻž āĻĒā§āĻšā§°ā§° āĻĒā§°āĻŋāĻŽāĻžāĻŖ āĻā§āĻ¨ āĻ āĻāĻļā§ āĻ¨āĻŋāĻ¯āĻŧāĻ¨ā§āĻ¤ā§ā§°āĻŖ āĻā§°ā§ ?
A. Retina | B. Iris | C. Cornea | D. Lens
Ans: B. Iris
Explanation: The iris controls the size of the pupil to regulate light entering the eye. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Iris āĻ āĻĒāĻŋāĻāĻĒāĻŋāĻ˛ā§° āĻāĻāĻžā§° āĻ¨āĻŋāĻ¯āĻŧāĻ¨ā§āĻ¤ā§ā§°āĻŖ āĻā§°āĻŋ āĻāĻā§āĻ¤ āĻĒā§ā§°ā§ąā§āĻļ āĻā§°āĻž āĻĒā§āĻšā§° āĻ¨āĻŋāĻ¯āĻŧāĻ¨ā§āĻ¤ā§ā§°āĻŖ āĻā§°ā§āĨ¤
Q28. The nearest star to Earth is: āĻĒā§āĻĨāĻŋā§ąā§ā§° āĻāĻāĻžāĻāĻ¤āĻā§ āĻāĻā§°ā§° āĻ¤āĻžā§°āĻāĻž āĻā§āĻ¨āĻā§ ?
A. Alpha Centauri | B. Sirius | C. Sun | D. Polaris
Ans: C. Sun
Explanation: The Sun is the closest star to Earth. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻ¸ā§ā§°ā§āĻ¯āĻ āĻĒā§āĻĨāĻŋā§ąā§ā§° āĻāĻāĻžāĻāĻ¤āĻā§ āĻāĻā§°ā§° āĻ¤āĻžā§°āĻāĻžāĨ¤
Q29. The pH of pure water is: āĻŦāĻŋāĻļā§āĻĻā§āĻ§ āĻĒāĻžāĻ¨ā§ā§° pH āĻŽāĻžāĻ¨ āĻāĻŋāĻŽāĻžāĻ¨ ?
A. 5 | B. 6 | C. 7 | D. 8
Ans: C. 7
Explanation: Pure water is neutral and has a pH value of 7. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻŦāĻŋāĻļā§āĻĻā§āĻ§ āĻĒāĻžāĻ¨ā§ āĻ¨āĻŋāĻ°āĻĒā§āĻā§āĻˇ āĻā§°ā§ āĻāĻ¯āĻŧāĻžā§° pH āĻŽāĻžāĻ¨ 7āĨ¤
Q30. Which metal is the best conductor of electricity ? :: āĻā§āĻ¨ āĻ§āĻžāĻ¤ā§ āĻŦāĻŋāĻĻā§āĻ¯ā§āĻ¤ā§° āĻ¸ā§°ā§āĻŦā§āĻ¤ā§āĻ¤āĻŽ āĻĒā§°āĻŋāĻŦāĻžāĻšā§ ?
A. Copper | B. Silver | C. Aluminium | D. Gold
Ans: B. Silver
Explanation: Silver has the highest electrical conductivity among metals. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Silver āĻ§āĻžāĻ¤ā§ā§° āĻŦāĻŋāĻĻā§āĻ¯ā§āĻ¤ āĻĒā§°āĻŋāĻŦāĻžāĻšāĻŋāĻ¤āĻž āĻāĻāĻžāĻāĻ¤āĻā§ āĻŦā§āĻāĻŋāĨ¤
Q31. Which blood group is known as the universal donor ? :: āĻā§āĻ¨ ā§°āĻā§āĻ¤ āĻā§āĻāĻ Universal Donor āĻŦā§āĻ˛āĻŋ āĻā§ā§ąāĻž āĻšāĻ¯āĻŧ ?
A. A | B. B | C. AB | D. O
Ans: D. O
Explanation: O negative blood can donate to all blood groups. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: O negative ā§°āĻā§āĻ¤ āĻ¸āĻāĻ˛ā§ ā§°āĻā§āĻ¤ āĻā§āĻāĻ āĻĻāĻžāĻ¨ āĻā§°āĻŋāĻŦ āĻĒāĻžā§°ā§āĨ¤
Q32. Which scientist discovered gravity ? :: āĻā§ā§°ā§āĻ¤ā§āĻŦāĻžāĻāĻ°ā§āĻˇāĻŖ āĻā§āĻ¨ āĻŦāĻŋāĻā§āĻāĻžāĻ¨ā§āĻ¯āĻŧā§ āĻā§ąāĻŋāĻˇā§āĻāĻžā§° āĻā§°āĻŋāĻāĻŋāĻ˛ ?
A. Einstein | B. Newton | C. Galileo | D. Faraday
Ans: B. Newton
Explanation: Isaac Newton discovered the law of gravitation. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Isaac Newton āĻ āĻā§ā§°ā§āĻ¤ā§āĻŦāĻžāĻāĻ°ā§āĻˇāĻŖā§° āĻ¨āĻŋāĻ¯āĻŧāĻŽ āĻā§ąāĻŋāĻˇā§āĻāĻžā§° āĻā§°āĻŋāĻāĻŋāĻ˛āĨ¤
Q33. The gas commonly used in balloons is: āĻŦā§āĻ˛ā§āĻ¨āĻ¤ āĻ¸āĻžāĻ§āĻžā§°āĻŖāĻ¤ā§ āĻŦā§āĻ¯ā§ąāĻšā§āĻ¤ āĻā§āĻ āĻā§āĻ¨āĻā§ ?
A. Oxygen | B. Hydrogen | C. Helium | D. Nitrogen
Ans: C. Helium
Explanation: Helium is lighter than air and non-flammable. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Helium āĻŦāĻžāĻ¯āĻŧā§āĻ¤āĻā§ āĻšāĻžāĻ˛āĻāĻž āĻā§°ā§ āĻā§āĻŦāĻ˛āĻž āĻ¨āĻ˛āĻāĻž āĻā§āĻāĨ¤
Q34. The process of converting liquid into gas is called: :: āĻ¤ā§°āĻ˛ āĻĒāĻĻāĻžā§°ā§āĻĨ āĻā§āĻāĻ˛ā§ āĻĒā§°āĻŋāĻŦāĻ°ā§āĻ¤āĻ¨ āĻšā§ā§ąāĻž āĻĒā§ā§°āĻā§ā§°āĻŋāĻ¯āĻŧāĻžāĻ āĻāĻŋ āĻā§ā§ąāĻž āĻšāĻ¯āĻŧ ?
A. Condensation | B. Evaporation | C. Freezing | D. Sublimation
Ans: B. Evaporation
Explanation: Evaporation is the process of liquid turning into vapor. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Evaporation āĻšā§āĻā§ āĻ¤ā§°āĻ˛ āĻĒāĻĻāĻžā§°ā§āĻĨ āĻŦāĻžāĻˇā§āĻĒāĻ˛ā§ āĻĒā§°āĻŋāĻŦāĻ°ā§āĻ¤āĻ¨ āĻšā§ā§ąāĻž āĻĒā§ā§°āĻā§ā§°āĻŋāĻ¯āĻŧāĻžāĨ¤
Q35. The SI unit of temperature is: :: āĻ¤āĻžāĻĒāĻŽāĻžāĻ¤ā§āĻ°āĻžā§° SI āĻāĻāĻ āĻāĻŋ ?
A. Celsius | B. Kelvin | C. Fahrenheit | D. Joule
Ans: B. Kelvin
Explanation: Kelvin is the SI unit of temperature. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Kelvin āĻšā§āĻā§ āĻ¤āĻžāĻĒāĻŽāĻžāĻ¤ā§āĻ°āĻžā§° SI āĻāĻāĻāĨ¤
Q36. Which element is essential for hemoglobin ? :: āĻšāĻŋāĻŽā§āĻā§āĻ˛ā§āĻŦāĻŋāĻ¨ā§° āĻŦāĻžāĻŦā§ āĻā§āĻ¨ āĻāĻĒāĻžāĻĻāĻžāĻ¨ āĻĒā§ā§°āĻ¯āĻŧā§āĻāĻ¨ā§āĻ¯āĻŧ ?
A. Calcium | B. Iron | C. Zinc | D. Copper
Ans: B. Iron
Explanation: Hemoglobin contains iron which carries oxygen in blood. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻšāĻŋāĻŽā§āĻā§āĻ˛ā§āĻŦāĻŋāĻ¨āĻ¤ Iron āĻĨāĻžāĻā§ āĻā§°ā§ āĻ āĻ āĻā§āĻ¸āĻŋāĻā§āĻ¨ āĻŦāĻšāĻ¨ āĻā§°ā§āĨ¤
Q37. The largest planet in the solar system is: :: āĻ¸ā§ā§°ā§āĻ¯ āĻŽāĻŖā§āĻĄāĻ˛ā§° āĻāĻāĻžāĻāĻ¤āĻā§ āĻĄāĻžāĻā§° āĻā§ā§°āĻš āĻā§āĻ¨āĻā§ ?
A. Earth | B. Jupiter | C. Saturn | D. Neptune
Ans: B. Jupiter
Q38. Which layer protects Earth from ultraviolet rays ? :: āĻĒā§āĻĨāĻŋā§ąā§āĻ UV ā§°āĻļā§āĻŽāĻŋā§° āĻĒā§°āĻž āĻā§āĻ¨ āĻ¸ā§āĻ¤ā§°ā§ āĻ¸ā§ā§°āĻā§āĻˇāĻž āĻĻāĻŋāĻ¯āĻŧā§ ?
A. Troposphere | B. Ozone layer | C. Mesosphere | D. Thermosphere
Ans: B. Ozone layer
Q39. The speed of sound in air is approximately: :: āĻŦāĻžāĻ¯āĻŧā§āĻ¤ āĻļāĻŦā§āĻĻā§° āĻāĻ¤āĻŋ āĻĒā§ā§°āĻžāĻ¯āĻŧ āĻāĻŋāĻŽāĻžāĻ¨ ?
A. 150 m/s | B. 343 m/s | C. 500 m/s | D. 1000 m/s
Ans: B. 343 m/s
Q40. Which part of the plant absorbs water ? :: āĻāĻĻā§āĻāĻŋāĻĻā§° āĻā§āĻ¨ āĻ āĻāĻļā§ āĻĒāĻžāĻ¨ā§ āĻļā§āĻˇāĻŖ āĻā§°ā§ ?
A. Leaf | B. Root | C. Stem | D. Flower
Ans: B. Root
Q41. The smallest unit of matter is: āĻĒāĻĻāĻžā§°ā§āĻĨā§° āĻ¸ā§°ā§āĻ¤āĻŽ āĻāĻāĻ āĻāĻŋ ?
A. Cell | B. Molecule | C. Atom | D. Proton
Ans: C. Atom
Q42. Which vitamin helps in blood clotting ? :: āĻā§āĻ¨ āĻāĻŋāĻāĻžāĻŽāĻŋāĻ¨ā§ ā§°āĻā§āĻ¤ āĻāĻŽāĻžāĻ¤ āĻ¸āĻšāĻžāĻ¯āĻŧ āĻā§°ā§ ?
A. Vitamin A | B. Vitamin C | C. Vitamin D | D. Vitamin K
Ans: D. Vitamin K
Q43. The chemical symbol of gold is: āĻ¸ā§āĻŖā§° ā§°āĻžāĻ¸āĻžāĻ¯āĻŧāĻ¨āĻŋāĻ āĻ¸āĻāĻā§āĻ¤ āĻāĻŋ ?
A. Ag | B. Au | C. Gd | D. Go
Ans: B. Au
Q44. Which organ pumps blood in the human body ? :: āĻŽāĻžāĻ¨ā§ą āĻļā§°ā§ā§°āĻ¤ āĻā§āĻ¨ āĻ āĻāĻāĻ ā§°āĻā§āĻ¤ āĻĒāĻžāĻŽā§āĻĒ āĻā§°ā§ ?
A. Brain | B. Heart | C. Lung | D. Liver
Ans: B. Heart
Q45. Which force keeps planets in orbit ? :: āĻā§ā§°āĻšāĻ¸āĻŽā§āĻšāĻ āĻāĻā§āĻˇāĻĒāĻĨāĻ¤ ā§°āĻžāĻā§ āĻā§āĻ¨ āĻŦāĻ˛ ?
A. Magnetic force | B. Gravitational force | C. Friction | D. Nuclear force
Ans: B. Gravitational force
Q46. The main gas in Earth's atmosphere is: āĻĒā§āĻĨāĻŋā§ąā§ā§° āĻŦāĻžāĻ¯āĻŧā§āĻŽāĻŖā§āĻĄāĻ˛āĻ¤ āĻŽā§āĻā§āĻ¯ āĻā§āĻ āĻā§āĻ¨āĻā§ ?
A. Oxygen | B. Carbon dioxide | C. Nitrogen | D. Hydrogen
Ans: C. Nitrogen
Q47. Which vitamin is good for eyesight ? :: āĻāĻā§ā§° āĻĻā§āĻˇā§āĻāĻŋā§° āĻŦāĻžāĻŦā§ āĻā§āĻ¨ āĻāĻŋāĻāĻžāĻŽāĻŋāĻ¨ āĻāĻĒāĻāĻžā§°ā§ ?
A. Vitamin A | B. Vitamin B | C. Vitamin C | D. Vitamin D
Ans: A. Vitamin A
Q48. Which scientist developed the theory of relativity ? :: Theory of Relativity āĻā§āĻ¨ āĻŦāĻŋāĻā§āĻāĻžāĻ¨ā§āĻ¯āĻŧā§ āĻŦāĻŋāĻāĻžāĻļ āĻā§°āĻŋāĻāĻŋāĻ˛ ?
A. Newton | B. Einstein | C. Galileo | D. Kepler
Ans: B. Einstein
Q49. The freezing point of water is: :: āĻĒāĻžāĻ¨ā§ā§° āĻāĻŽāĻž āĻŦāĻŋāĻ¨ā§āĻĻā§ āĻāĻŋāĻŽāĻžāĻ¨ ?
A. 0°C | B. 10°C | C. 32°C | D. −5°C
Ans: A. 0°C
Q50. The study of living organisms is called: :: āĻā§ā§ąāĻŋāĻ¤ āĻŦāĻ¸ā§āĻ¤ā§āĻ¸āĻŽā§āĻšā§° āĻ āĻ§ā§āĻ¯āĻ¯āĻŧāĻ¨āĻ āĻāĻŋ āĻā§ā§ąāĻž āĻšāĻ¯āĻŧ ?
A. Physics | B. Chemistry | C. Biology | D. Geology
Ans: C. Biology
Explanation: Biology is the branch of science that studies living organisms. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž : āĻā§ā§ą āĻā§°ā§ āĻā§ā§ąāĻŋāĻ¤ āĻŦāĻ¸ā§āĻ¤ā§āĻ¸āĻŽā§āĻšā§° āĻ āĻ§ā§āĻ¯āĻ¯āĻŧāĻ¨āĻ Biology āĻŦā§āĻ˛āĻŋ āĻā§ā§ąāĻž āĻšāĻ¯āĻŧāĨ¤
Q51. What is the full form of DNA ? :: DNA ā§° āĻĒā§ā§°ā§āĻŖ ā§°ā§āĻĒ āĻāĻŋ ?
A. Deoxyribonucleic Acid B. Deoxyribose Acid C. Double Nucleic Acid D. Dynamic Nucleic Acid
Ans: A. Deoxyribonucleic Acid
Explanation: DNA stores genetic information in living organisms. :: āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: DNA āĻ āĻā§ā§ąā§° āĻŦāĻāĻļāĻāĻ¤ āĻ¤āĻĨā§āĻ¯ āĻ¸āĻā§°āĻā§āĻˇāĻŖ āĻā§°ā§āĨ¤
Q52. What is the boiling point of pure water at sea level ? :: āĻ¸āĻŽā§āĻĻā§ā§°āĻĒā§āĻˇā§āĻ āĻ¤ āĻŦāĻŋāĻļā§āĻĻā§āĻ§ āĻĒāĻžāĻ¨ā§ā§° āĻ¸ā§āĻĢā§āĻāĻ¨āĻžāĻāĻ āĻāĻŋāĻŽāĻžāĻ¨ ?
A. 90°C | B. 95°C | C. 100°C | D. 110°C
Ans: C. 100°C
Explanation: Pure water boils at 100°C at normal atmospheric pressure. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž : āĻ¸āĻžāĻ§āĻžā§°āĻŖ āĻŦāĻžāĻ¯āĻŧā§āĻŽāĻŖā§āĻĄāĻ˛ā§āĻ¯āĻŧ āĻāĻžāĻĒāĻ¤ āĻŦāĻŋāĻļā§āĻĻā§āĻ§ āĻĒāĻžāĻ¨ā§ā§° āĻ¸ā§āĻĢā§āĻāĻ¨āĻžāĻāĻ 100°CāĨ¤