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MCQ practice · SSC Chemistry Board questions · Chapter 6: Concept of Mole and Chemical Counting

Dhaka Board 2023

Of the stimulus:

  1. i. The gas formed in vessel A is acidic
  2. ii. The reaction in vessel B is a redox reaction
  3. iii. 1 mole of the compound formed in vessel B = 62 g

Think it through first, then pick an option.

  1. a i and ii
  2. b ii and iii
  3. c i and iii
  4. d i, ii and iii
Answer and explanation

Correct answer: c i and iii

i is true: CO₂ is an acidic oxide. iii is true: in B, H₂CO₃ = 2 + 12 + 48 = 62, so 1 mole = 62 g. ii is false: not redox.

Why the other options are wrong

  • a i and ii: ii is wrong: CO₂ + H₂O → H₂CO₃ changes no oxidation number, so it is not redox; and the true i is left out.
  • b ii and iii: ii is wrong: the reaction is not redox; and the true i (CO₂ is acidic) is left out.
  • d i, ii and iii: ii is wrong: CO₂ + H₂O → H₂CO₃ is not redox, so not all three are true.

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