Chemistry MCQs – Set 3: Advanced Questions for UPSC/PCS Exam Prep

  1. The blue color of CuSO₄·5H₂O is due to –
    (A) Cu⁺
    (B) Water of crystallization
    (C) Cu²⁺ ions
    (D) SO₄²⁻ ions
    Answer: (C)
  2. Isobars are atoms with –
    (A) Same atomic number
    (B) Same mass number
    (C) Same number of neutrons
    (D) Same number of electrons
    Answer: (B)
  3. The basicity of H₂SO₄ is –
    (A) 1
    (B) 2
    (C) 3
    (D) 0
    Answer: (B)
  4. Which compound turns red litmus blue?
    (A) HCl
    (B) NaOH
    (C) CH₃COOH
    (D) H₂SO₄
    Answer: (B)
  5. The ore of iron is –
    (A) Bauxite
    (B) Magnetite
    (C) Dolomite
    (D) Galena
    Answer: (B)
  6. Which gas is used in fluorescent lamps?
    (A) Helium
    (B) Argon
    (C) Hydrogen
    (D) Methane
    Answer: (B)
  7. The electrolyte used in lead-acid battery is –
    (A) HCl
    (B) NaOH
    (C) H₂SO₄
    (D) KOH
    Answer: (C)
  8. The most ductile metal is –
    (A) Gold
    (B) Silver
    (C) Copper
    (D) Platinum
    Answer: (A)
  9. The formula of Plaster of Paris is –
    (A) CaSO₄
    (B) CaSO₄·1/2H₂O
    (C) CaCO₃
    (D) Ca(OH)₂
    Answer: (B)
  10. The substance used for bleaching dirty clothes is –
    (A) Baking soda
    (B) Vinegar
    (C) Bleaching powder
    (D) Alum
    Answer: (C)
  11. Tincture of iodine contains –
    (A) Iodine + alcohol
    (B) Iodine + water
    (C) Iodine + glycerin
    (D) Iodine + oil
    Answer: (A)
  12. The chemical name of vitamin C is –
    (A) Folic acid
    (B) Acetic acid
    (C) Ascorbic acid
    (D) Citric acid
    Answer: (C)
  13. The gas used for artificial ripening of fruits is –
    (A) Ethane
    (B) Acetylene
    (C) Ethylene
    (D) Propane
    Answer: (C)
  14. Which element shows variable valency?
    (A) Calcium
    (B) Carbon
    (C) Iron
    (D) Sodium
    Answer: (C)
  15. The neutralization reaction produces –
    (A) Salt only
    (B) Acid only
    (C) Base only
    (D) Salt and water
    Answer: (D)
  16. Acids react with metals to release –
    (A) Oxygen
    (B) Hydrogen
    (C) Carbon dioxide
    (D) Chlorine
    Answer: (B)
  17. The unit of rate constant for a first-order reaction is –
    (A) s⁻¹
    (B) mol/L·s
    (C) mol⁻¹·L·s⁻¹
    (D) s
    Answer: (A)
  18. Greenhouse effect is mainly due to –
    (A) CO₂
    (B) O₂
    (C) NO₂
    (D) N₂
    Answer: (A)
  19. The radioactive isotope used in cancer treatment is –
    (A) Cobalt-60
    (B) Uranium-235
    (C) Carbon-14
    (D) Iodine-131
    Answer: (A)
  20. The electrolyte used in electroplating is –
    (A) Water
    (B) Salt of plating metal
    (C) Acid
    (D) Alcohol
    Answer: (B)
  21. The pH scale ranges from –
    (A) 0 to 10
    (B) 1 to 12
    (C) 0 to 14
    (D) 1 to 100
    Answer: (C)
  22. A catalyst –
    (A) Increases activation energy
    (B) Decreases equilibrium constant
    (C) Speeds up reaction without being consumed
    (D) Alters concentration
    Answer: (C)
  23. The brown ring test is used to detect –
    (A) Nitrate
    (B) Sulfate
    (C) Chloride
    (D) Carbonate
    Answer: (A)
  24. The chemical formula of laughing gas is –
    (A) NO
    (B) N₂O
    (C) NO₂
    (D) NH₃
    Answer: (B)
  25. The basicity of acetic acid is –
    (A) 2
    (B) 1
    (C) 3
    (D) 4
    Answer: (B)
  26. Which element is liquid at room temperature?
    (A) Mercury
    (B) Sodium
    (C) Potassium
    (D) Calcium
    Answer: (A)
  27. The IUPAC name of CH₃COOH is –
    (A) Acetone
    (B) Ethanoic acid
    (C) Acetic acid
    (D) Methylformic acid
    Answer: (B)
  28. The metal used in thermite welding is –
    (A) Iron
    (B) Aluminum
    (C) Zinc
    (D) Nickel
    Answer: (B)
  29. The formula of gypsum is –
    (A) CaSO₄·1/2H₂O
    (B) CaSO₄·2H₂O
    (C) CaCO₃
    (D) Ca(OH)₂
    Answer: (B)
  30. The chemical name of table salt is –
    (A) Sodium bicarbonate
    (B) Sodium chloride
    (C) Sodium carbonate
    (D) Potassium chloride
    Answer: (B)
  31. Atomic size across a period –
    (A) Increases
    (B) Decreases
    (C) Remains same
    (D) First increases then decreases
    Answer: (B)
  32. Which has maximum ionization energy?
    (A) Li
    (B) Na
    (C) K
    (D) He
    Answer: (D)
  33. The strongest acid among the following is –
    (A) HCl
    (B) H₂SO₄
    (C) HNO₃
    (D) HClO₄
    Answer: (D)
  34. Which of the following is a noble metal?
    (A) Iron
    (B) Copper
    (C) Platinum
    (D) Zinc
    Answer: (C)
  35. The most electronegative element is –
    (A) Fluorine
    (B) Oxygen
    (C) Chlorine
    (D) Nitrogen
    Answer: (A)
  36. A salt of a weak acid and strong base is –
    (A) Acidic
    (B) Basic
    (C) Neutral
    (D) None
    Answer: (B)
  37. The formula of sodium carbonate is –
    (A) NaHCO₃
    (B) Na₂CO₃
    (C) NaCl
    (D) NaOH
    Answer: (B)
  38. Aromaticity is associated with –
    (A) High molecular mass
    (B) Saturation
    (C) Planar rings with delocalized π-electrons
    (D) Alkyl groups
    Answer: (C)
  39. The rate of reaction increases with –
    (A) Decrease in temperature
    (B) Use of inhibitor
    (C) Increase in surface area
    (D) Decrease in concentration
    Answer: (C)
  40. Fullerenes are –
    (A) Metals
    (B) Allotropes of carbon
    (C) Acids
    (D) Salts
    Answer: (B)
  41. The first organic compound synthesized in lab was –
    (A) Acetic acid
    (B) Methane
    (C) Urea
    (D) Ethanol
    Answer: (C)
  42. The covalent bond angle in methane is –
    (A) 90°
    (B) 109.5°
    (C) 120°
    (D) 180°
    Answer: (B)
  43. The anode in galvanic cell is –
    (A) Negative
    (B) Positive
    (C) Neutral
    (D) Inert
    Answer: (A)
  44. The oxidation state of Fe in FeCl₃ is –
    (A) +2
    (B) +1
    (C) +3
    (D) 0
    Answer: (C)
  45. The metal which forms amphoteric oxide is –
    (A) Sodium
    (B) Potassium
    (C) Aluminum
    (D) Calcium
    Answer: (C)
  46. Ozone (O₃) is –
    (A) Monoatomic
    (B) Triatomic
    (C) Diatomic
    (D) Polyatomic
    Answer: (B)
  47. The ion responsible for hardness of water is –
    (A) Na⁺
    (B) Ca²⁺
    (C) Cl⁻
    (D) OH⁻
    Answer: (B)
  48. Which solution shows Tyndall effect?
    (A) Salt solution
    (B) Sugar solution
    (C) Milk
    (D) Alcohol
    Answer: (C)
  49. The basic structure of protein is –
    (A) Amino acid
    (B) Carbohydrate
    (C) Fatty acid
    (D) Vitamin
    Answer: (A)
  50. The catalyst used in contact process is –
    (A) Iron
    (B) Platinum
    (C) Vanadium pentoxide
    (D) Nickel
    Answer: (C)
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