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MCQ practice · SSC Chemistry Board questions · Chapter 5: Chemical Bond

Dinajpur Board 2025

The gas 'X' formed:

  1. i. it can turn lime water milky
  2. ii. its aqueous solution tastes sour
  3. iii. the latent valency of the central atom is 2

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: a i and ii

X is CO₂: it turns lime water milky (i) and gives a sour solution in water (ii). iii is false: in CO₂ carbon's active valency is 4 and its highest is also 4, so the latent valency is 4 − 4 = 0.

Why the other options are wrong

  • b ii and iii: iii is false: in CO₂ carbon's latent valency is 4 − 4 = 0, not 2 (2 is for CO). Also i is true, so this leaves out a true statement.
  • c i and iii: iii is false: in CO₂ carbon's latent valency is 0; 2 is for CO. Also ii is true, so this leaves out a true statement.
  • d i, ii and iii: iii is false: in CO₂ carbon's active valency 4 equals its highest 4, so the latent valency is 0.

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