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MCQ practice · SSC Chemistry Board questions · Chapter 7: Chemical Reactions

Cumilla Board 2025

If the solutions in vessels A and B are mixed together-

  1. i. a neutralization reaction takes place
  2. ii. oxidation-reduction takes place
  3. iii. CO₂ gas is produced

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

Na₂CO₃ is basic and HCl is an acid, so mixing them neutralizes (i) and gives NaCl, water and CO₂ gas (iii). No electrons are exchanged, so ii is false.

Why the other options are wrong

  • a i and ii: i is true, but ii is false: in Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂ no oxidation number changes. iii is left out.
  • b ii and iii: ii is false: no oxidation number of Na, C, O, H or Cl changes and no electrons move. And i is true, so it cannot be left out.
  • d i, ii and iii: ii is not true: this reaction is non-redox, so not all three are true.

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