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Top 100 Chemistry MCQ for Competitive Exams

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Top 100 Chemistry MCQ for Competitive Exams

Are you preparing for competitive exams? Chemistry plays a crucial role in various competitive exams.

In this article, we’ve compiled the Top 100 Chemistry MCQ for Competitive Exams that have already appeared in various government exams.  Whether you’re revising or practising for your next big exam, this guide will be a valuable resource in your Exam preparation journey.

Whether you are preparing for PSC, SSC, Railways, Banking, TET, or any state-level or national-level competitive exams, these carefully selected multiple-choice questions [MCQs] will guide you toward success. Let’s practice these Chemistry MCQs and take your preparation to the next level!

1. Bhopal Gas Tragedy was caused due to the leakage of___
(A) Methyl Isocyanate
(B) Nitrogen dioxide
(C) Sulphur dioxide
(D) Carbon monoxide

Answer: (A) Methyl Isocyanate

2. Which of the following is an inorganic gaseous pollutant of air?
(A) Phosgene
(B) Hydrogen Cyanide
(C) Hydrogen Sulphide
(D) Methane

Answer: (C) Hydrogen Sulphide

3. In dry cells, which of the following are used as electrolytes?
(A) Ammonium Chloride and Zinc Chloride
(B) Sodium Chloride and Calcium Chloride
(C) Magnesium Chloride and Zinc Chloride
(D) Ammonium Chloride and Calcium Chloride

Answer: (A) Ammonium Chloride and Zinc Chloride

See More:- Top 100 Indian Geography MCQ questions

4. Which one of the following is incorrect? 
(A) Theory of evolution was propounded by Charles Darwin
(B) The breaking apart of the nucleus of an atom is called fusion
(C) Dry ice is nothing but solid Carbon dioxide
(D) Telephone was invented by Graham Bell

Answer: (B) The breaking apart of the nucleus of an atom is called fusion

5. Which one of the following pairs is correctly matched?
(A) Silver Iodide – Horn Silver
(B) Silver Chloride – Artificial rain
(C) Zinc Phosphide – Rat poison
(D) Zinc Sulphide – Philosopher’s wool

Answer: (C) Zinc Phosphide – Rat poison

6. What element is used in the matchbox?
(A) Graphite
(B) Phosphorus
(C) Silicon
(D) Sodium

Answer: (B) Phosphorus

7. Which one of the following is used in the manufacture of soaps?
(A) Vegetable oil
(B) Mobil oil
(C) Kerosene oil
(D) Cutting oil

Answer: (A) Vegetable oil

See More:- Top 100 World Geography MCQ

8. Which of the following oil is an extract of clove oil? 
(A) Ethanol
(B) Eugenol
(C) Methanol
(D) Benzaldehyde

Answer: (B) Eugenol

9. Which of the following method is used for measuring the age of the earth? 
(A) Carbon dating process
(B) Biotechnology Law
(C) Biological clock method
(D) Uranium process

Answer: (D) Uranium process

10. Which of the following is a common refrigerant used in the domestic refrigerator? 
(A) Neon
(B) Oxygen
(C) Freon
(D) None of these

Answer: (C) Freon

11. Which one of the following acids, is formed during the change of milk into curd?
(A) Acetic acid
(B) Ascorbic acid
(C) Citric acid
(D) Lactic acid

Answer: (D) Lactic acid

12. Which one of the following substances is used in the preservation of foodstuff?
(A) Citric Acid
(B) Potassium Chloride
(C) Sodium Benzoate
(D) Sodium Chloride

Answer: (C) Sodium Benzoate

13. Refrigeration helps in food preservation by_____
(A) Killing the germs
(B) Reducing the rate of biochemical reactions
(C) Destroying enzyme action
(D) Sealing the food with a layer of ice

Answer: (B) Reducing the rate of biochemical reactions

14. Indane gas is a mixture of_____
(A) Butane and Hydrogen
(B) Butane and Oxygen
(C) Butane and Propane
(D) Methane and Oxygen

Answer: (C) Butane and Propane

15. Biogas mainly consists of______
(A) Carbon dioxide and Hydrogen
(B) Hydrogen and Methane
(C) Cardon dioxide and Methane
(D) Hydrogen and Oxygen

Answer: (C) Carbon dioxide and Methane

16. Who among the following invented the ‘Gobar Gas’ system?
(A) C.V. Raman
(B) J.C. Bose
(C) S.V. Desai
(D) H. Khurana

Answer: (C) S.V. Desai

17. Which one of the following is not an explosive?
(A) Trinitrotoluene (TNT)
(B) Trinitroglycerine
(C) Cyclotrimethylene Trinitramine (RDX)
(D) Nitrochloroform

Answer: (D) Nitrochloroform

18. Which acid is found in Vinegar?

(A) Lactic acid
(B) Citric acid
(C) Malic acid
(D) Acetic acid

Answer: (D) Acetic acid

19. Accumulation of which one of the following in the muscles leads to fatigue?
(A) Lactic acid
(B) Benzoic acid
(C) Pyruvic acid
(D) Uric acid

Answer: (A) Lactic acid

20. Which one of the following polymer is widely used for making bulletproof materials?
(A) Polyvinyl chloride
(B) Polyamides
(C) Polyethylene
(D) Polycarbonates

Answer: (B) Polyamides

21. A polymer used for making non-stick surface coating for utensils is____
(A) Polyvinyl chloride
(B) Teflon
(C) Polystyrene
(D) Polypropylene

Answer: (B) Teflon

22. Which one of the following was used as a chemical weapon in the First World War?
(A) Carbon monoxide
(B) Hydrogen cyanide
(C) Mustard gas
(D) Water gas

Answer: (C) Mustard gas

23. Leakage of which of the following gases had caused the Bhopal Gas Tragedy?
(A) Methyl isocyanate
(B) Carbon mono-oxide
(C) Nitric oxide
(D) Sulphur dioxide

Answer: (A) Methyl isocyanate

24. Which one of the following chemical helps in fruit ripening?
(A) Ethephon
(B) Atrazine
(C) Isoproturan
(D) Malathion

Answer: (A) Ethephon

25. Which of the following gas mixture is used in welding gas?
(A) Acetylene and Hydrogen
(B) Oxygen and Acetylene
(C) Hydrogen and Oxygen
(D) Hydrogen and Helium

Answer: (B) Oxygen and Acetylene

26. Which one of the following pairs is not correctly matched?
(A) Fullerene – Organic compounds containing fluorine
(B) Dry Ice – Solid carbon dioxide
(C) Keratin – Protein found in the outer layer of human skin
(D) Mustard gas – Poisonous liquid used in chemical warfare

Answer: (A) Fullerene – Organic compounds containing fluorine

27. What is the liquid used by goldsmiths to melt gold?

(A) Nitric acid and Sulphuric acid
(B) Nitric acid and Hydrochloric acid
(C) Sulphuric acid and Hydrochloric acid
(D) Citric acid and Benzoic acid

Answer: (B) Nitric acid and Hydrochloric acid

28. Baking soda is_____
(A) Sodium Hydrogen Carbonate
(B) Sodium Dihydrogen Carbonate
(C) Disodium Hydrogen Carbonate
(D) Sodium Carbonate

Answer: (A) Sodium Hydrogen Carbonate

29. Which chemical compound is present in Bleaching Powder?
(A) Calcium Hydroxide
(B) Calcium Oxychloride
(C) Calcium Carbonate
(D) Ammonium Chloride

Answer: (B) Calcium Oxychloride

30. Which one of the following substances is used in photography and also as an antichlor?
(A) Chrome red
(B) Sodium thiosulphate
(C) Hydrogen peroxide
(D) Calomel

Answer: (B) Sodium thiosulphate

31. Which of the following gas is used as tear gas? 
(A) H₂
(B) SO₂
(C) NH₃
(D) Cl₂

Answer: (D) Cl₂ (Chlorine)

32. Which is used as Laughing gas?
(A) Nitrous oxide
(B) Nitrogen dioxide
(C) Nitrogen trioxide
(D) Nitrogen tetra oxide

Answer: (A) Nitrous oxide

33. What is heavy water?
(A) Oxygen + Heavy Hydrogen
(B) Hydrogen + Oxygen
(C) Hydrogen + New Oxygen
(D) Heavy Hydrogen + Heavy

Answer: (A) Oxygen + Heavy Hydrogen

34. Heavy water is that water____
(A) The temperature of which is kept constant at 4ºC
(B) In which insoluble salts of Calcium and Potassium are present
(C) In which isotopes takes place of Hydrogen
(D) In which isotopes takes place of Oxygen

Answer: (C) In which isotopes takes place of Hydrogen

35. The gas used in the manufacture of Vanaspati Ghee from Vanaspati Oil is____
(A) Hydrogen
(B) Oxygen
(C) Nitrogen
(D) Carbon dioxide

Answer: (A) Hydrogen

36. Chemically Dry Ice is___

(A) Solid sulphur
(B) Ice made from distilled water
(C) Mixture of ice and common salt
(D) Solid carbon dioxide

Answer: (D) Solid carbon dioxide

37. A Tubelight is filled with____
(A) Sodium vapour
(B) Argon gas at low pressure
(C) Mercury vapour at low pressure
(D) Both (B) and (C)

Answer: (D) Both (B) and (C)

38. Which one of the following types of coal contains a higher percentage of Carbon than the rest type of ?
(A) Bituminous coal
(B) Lignite
(C) Peat
(D) Anthracite

Answer: (D) Anthracite

39. Which of the following elements are included in stainless steel?
(A) Chromium, Nickel and Iron
(B) Nickel, Iron and Carbon
(C) Iron, Chromium, Manganese and Carbon
(D) Iron, Zinc, Chromium and Carbon

Answer: (A) Chromium, Nickel and Iron

40. Bronze is an alloy of____
(A) Copper and Tin
(B) Copper and Silver
(C) Copper and Zinc
(D) Copper and Lead

Answer: (A) Copper and Tin

41. In the case of rusting, the weight of iron___
(A) Increases
(B) Decreases
(C) Remains the same
(D) Uncertain

Answer: (A) Increases

42. Brass is a combination of what metals? 
(A) Copper and Nickel
(B) Copper and Tin
(C) Copper and Zinc
(D) Copper + Zinc and Nickel

Answer: (C) Copper and Zinc

43. Bauxite is an ore of which of the following metals?
(A) Iron
(B) Copper
(C) Aluminium
(D) Silver

Answer: (C) Aluminium

44. Mica is a _____
(A) Good conductor of heat and bad conductor of electricity
(B) Bad conductor of both heat and electricity
(C) Good conductor of heat and electricity both
(D) Bad conductor of heat and good conductor of electricity

Answer: (A) Good conductor of heat and bad conductor of electricity

45. The chemical structure of the pearl is _____
(A) Calcium Carbonate
(B) Calcium Carbonate & Magnesium Carbonate
(C) Calcium Chloride
(D) Calcium Sulphate

Answer: (A) Calcium Carbonate

46. The chemical composition of diamond is_____
(A) Carbon
(B) Nitrogen
(C) Nickel
(D) Zinc

Answer: (A) Carbon

47. Pasteurization is a process by which ____
(A) Milk is preserved at a very low temperature for 24 hours
(B) Milk is heated for 8 hours
(C) First milk is heated up to a longer time and then cooled suddenly within specified time
(D) None of the above

Answer: (C) First milk is heated up to a longer time and then cooled suddenly within specified time

48. The technique of chromatography is used to_____
(A) Identify colour substances
(B) Determine the structure of substances
(C) Dry distillation of colouring substances
(D) Separate the substances from a mixture

Answer: (D) Separate the substances from a mixture

49. Example of corrosion is_____
(A) Black coating on Silver
(B) Green coating on Copper
(C) Brown coating on Iron
(D) Above three

Answer: (D) Above three

50. The atoms, in which the number of protons is same but the number of neutrons is different, are known as___
(A) Isobars
(B) Isomers
(C) Isotones
(D) Isotopes

Answer: (D) Isotopes

51. Radioactivity is measured by____
(A) Hydrometer
(B) Geiger Counter
(C) Seismometer
(D) Ammeter

Answer: (B) Geiger Counter

52. Which of the following statement about molecular structure is correct? 
(A) Neutron and electron are found inside the nucleus and protons revolves around the nucleus
(B) Electron and proton are inside the nucleus and neutron revolve around the nucleus
(C) Proton and neutron are inside the nucleus and electrons revolve around the nucleus
(D) Proton, neutron and electron all are inside the nucleus

Answer: (C) Proton and neutron are inside the nucleus and electrons revolve around the nucleus

53. Constituents of the atomic nucleus are___
(A) Electron and proton
(B) Electron and neutron
(C) Proton and neutron
(D) Proton, neutron and electron

Answer: (C) Proton and neutron

54. Approximately, how many different chemical elements exist in the Earth? 
(A) 300
(B) 250
(C) 200
(D) 100

Answer: (D) 100

55. Which one of the following is present in the largest amount in terms of percent by mass in the Earth’s crust?
(A) Silicon
(B) Oxygen
(C) Carbon
(D) Calcium

Answer: (B) Oxygen

56. Which of the following is the most common element in the Universe?
(A) Hydrogen
(B) Oxygen
(C) Nitrogen
(D) Carbon

Answer: (A) Hydrogen

57. The chemical composition of diamond is_____
(A) Carbon
(B) Nitrogen
(C) Nickel
(D) Zinc

Answer: (A) Carbon

58. Which is the hardest in the following?
(A) Diamond
(B) Glass
(C) Quartz
(D) Platinum

Answer: (A) Diamond

59. Which one of the following metals is liquid at ordinary temperature?
(A) Lead
(B) Nickel
(C) Mercury
(D) Tin

Answer: (C) Mercury

60. Which of the following is lighter than water?
(A) Aluminium
(B) Sodium
(C) Magnesium
(D) Manganese

Answer: (B) Sodium

61. Iron is obtained from___
(A) Limestone
(B) Pitch-blende
(C) Monazite Sand
(D) Hematite

Answer: (D) Hematite

62. Galvanized iron is coated with_____
(A) Aluminium
(B) Galena
(C) Silver
(D) Zinc

Answer: (D) Zinc

63. Out of the following which is not an alloy? 
(A) Steel
(B) Brass
(C) Bronze
(D) Copper

Answer: (D) Copper

64. Which one of the following alloys is called an amalgam?
(A) Zinc – Copper
(B) Copper – Tin
(C) Mercury – Zinc
(D) Lead – Zinc

Answer: (C) Mercury – Zinc

65. Which lubricant is used for heavy machines?
(A) Bauxite
(B) Phosphorus
(C) Graphite
(D) Silicon oil

Answer: (C) Graphite

66. The substance used as moderator and coolant both, in nuclear reactors is____
(A) Ordinary water
(B) Heavy water
(C) Liquid Ammonia
(D) Liquid Hydrogen

Answer: (B) Heavy water

67. Which is the purest form of water?
(A) Tap water
(B) Sea water
(C) Rain water
(D) Distilled water

Answer: (C) Rain water

68. Which gas is used in the purification of drinking water?
(A) Helium
(B) Chlorine
(C) Fluorine
(D) Carbon Dioxide

Answer: (B) Chlorine

69. Percentage amount (by volume) of which one of the following gas is lowest in the atmosphere?
(A) Argon
(B) Carbon dioxide
(C) Nitrogen
(D) Oxygen

Answer: (B) Carbon dioxide

70. Easily soluble in water____
(A) Carbon
(B) Nitrogen
(C) Ammonia
(D) Iodine

Answer: (C) Ammonia

71. A solution turns red litmus blue. The pH of solution is______
(A) 7
(B) 1
(C) 5
(D) None of these

Answer: (D) None of these

72. Which one of the following substances is used in photography and also as an antichlor?
(A) Chrome red
(B) Sodium thiosulphate
(C) Hydrogen peroxide
(D) Calomel

Answer: (B) Sodium thiosulphate

73. Which chemical compound is present in Bleaching Powder?
(A) Calcium Hydroxide
(B) Calcium Oxychloride
(C) Calcium Carbonate
(D) Ammonium Chloride

Answer: (B) Calcium Oxychloride

74. Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?
(A) Hydrogen, Oxygen, Sodium
(B) Carbon, Hydrogen, Nitrogen
(C) Oxygen, Calcium, Phosphorus
(D) Carbon, Hydrogen, Potassium

Answer: (B) Carbon, Hydrogen, Nitrogen

75. Which of the following is correctly matched? 
1. Biogas – Insecticide
2. Electro-cardiography – Heart disorder
3. D.D.T. – Cow dung
4. Nicotine – Tobacco
Code
(A) 1, 2 and 4
(B) 2, 3 and 4
(C) 2 and 3
(D) 2 and 4

Answer: (D) 2 and 4

76. Which one of the following is also known as ‘wood spirit’?
(A) Methyl alcohol
(B) Ethyl alcohol
(C) Ethylene glycol
(D) Glycerol

Answer: (A) Methyl alcohol

77. Which of the following is not a Natural polymer? 
(A) Wool
(B) Silk
(C) Leather
(D) Nylon

Answer: (D) Nylon

78. Which one of the following is a natural polymer? 
(A) Bakelite
(B) Silk
(C) Kevlar
(D) Lexan

Answer: (B) Silk

79. Which one of the following acids is used in the manufacturing of baking powder?
(A) Oxalic acid
(B) Lactic acid
(C) Tartaric acid
(D) Benzoic acid

Answer: (C) Tartaric acid

80. Which one of the following organic acids is abundant in grapes, tamarind and banana?
(A) Acetic acid
(B) Citric acid
(C) Lactic acid
(D) Tartaric acid

Answer: (D) Tartaric acid

81. Which one of the following is another name of RDX?
(A) Cyanohydrin
(B) Dextran
(C) Cyclohexane
(D) Cyclonite

Answer: (D) Cyclonite

82. Which one of the following is used as an explosive? 
(A) Phosphorus Trichloride
(B) Mercuric Oxide
(C) Graphite
(D) Nitroglycerine

Answer: (D) Nitroglycerine

83. Which of the following fossil fuels is the cleanest fuel? 
(A) Coal
(B) Petrol
(C) Natural gas
(D) Diesel

Answer: (C) Natural gas

84. Diesel used in heavy vehicles for_____
(A) Extra mileage and save engine
(B) Low expense and save the fuel
(C) High power and financially secure
(D) Being cheaper than low petrol

Answer: (C) High power and financially secure

85. The fuel used in a diesel engine______
(A) Vapour of diesel and air
(B) Diesel only
(C) Mixture of diesel and petrol
(D) Mixture of diesel, air and petrol

Answer: (A) Vapour of diesel and air

86. What is the main component of L.P.G.? 

(A) Methane
(B) Ethane
(C) Propane
(D) Butane

Answer: (D) Butane

87. What is the full form of CNG?
(A) Compressed Natural Gas
(B) Cyanogen Natural Gas
(C) Condensed Nitrogen Gas
(D) Controlled Natural Gas

Answer: (A) Compressed Natural Gas

88. Gasohol is a mixture of ____
(A) Ethyl alcohol + Petrol
(B) Natural gas + Ethyl alcohol
(C) Any gas dissolved in alcohol
(D) Ethyl alcohol + Kerosene oil

Answer: (A) Ethyl alcohol + Petrol

89. Milk openly placed for sometime becomes sour due to___

(A) Carbonic acid
(B) Lactic acid
(C) Citric acid
(D) Acetic acid

Answer: (B) Lactic acid

90. Which one of the following forms an irreversible complex with a haemoglobin of the blood?
(A) Carbon Dioxide
(B) Pure Nitrogen gas
(C) Carbon Monoxide
(D) A mixture of Carbon Dioxide and Helium

Answer: (C) Carbon Monoxide

91. Milk is an example of____

(A) A gel
(B) A foam
(C) An emulsion
(D) A suspension

Answer: (C) An emulsion

92. What is detergent?
(A) Soap
(B) Medicine
(C) Catalyst
(D) Refining agent

Answer: (D) Refining agent

93.   Which one of the following fertilizers leaves maximum acidity in the soil?

(A) Urea
(B) Ammonium Sulphate
(C) Ammonium Nitrate
(D) Calcium Ammonium Nitrate

Answer: (B) Ammonium Sulphate

94. Which of the following is not a chemical fertilizer?

(A) Urea
(B) Sodium Sulphate
(C) Super Phosphate
(D) Potassium Nitrate

Answer: (B) Sodium Sulphate

95. Which of the following is used as a mosquito repellent?

(A) Pyrethrum
(B) Rotenone
(C) Ephedrine
(D) None of these

Answer: (A) Pyrethrum

96. Which one of the following is used as rat poison? 

(A) Zinc Sulphide
(B) Lead Sulphide
(C) Calcium Phosphate
(D) Zinc Phosphide

Answer: (D) Zinc Phosphide

97. Which one of the following solutions of electrolytes is used in the car battery? 

(A) Sodium sulphate
(B) Nitric acid
(C) Sulphuric acid
(D) Potassium nitrate

Answer: (C) Sulphuric acid

98. Which is used in Dry Washing?

(A) Petrol
(B) Benzene
(C) Alcohol
(D) All of these

Answer: (D) All of these

99. Which one of the following is not correctly matched?

(A) Magnesium – Fireworks
(B) Uranium – Atom bomb
(C) Silver – Electric bulb
(D) Zinc – Galvanization

Answer: (C) Silver – Electric bulb

100. Which of the following archaeological samples is adopted to determine the age of firewood bone and shell? 

(A) Uranium-238
(B) Argon-Isotopes
(C) Carbon-14
(D) Strontium-90

Answer: (C) Carbon-14


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