Q96 / 270 · NDA 2025 (Phase 2) · General Ability

The reaction that occurs on passing carbon dioxide gas through lime water is

  • A
    $CaCO_3 + H_2O + CO_2 \rightarrow Ca(HCO_3)_2$
  • Correct answer
    B
    $Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$
  • C
    $CaO + CO_2 \rightarrow CaCO_3$
  • D
    $CaCl_2 + H_2O + CO_2 \rightarrow CaCO_3 + 2HCl$

Solution

Lime water is an aqueous solution of calcium hydroxide, $Ca(OH)_2$.

When carbon dioxide gas is passed through lime water, it reacts with calcium hydroxide to form a white precipitate of calcium carbonate and water.

The chemical equation for this reaction is:
$Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$

Answer: $Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$

Hence, the correct answer is option: 'B'.

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