Question

What happens when calcium is treated with water?

(i) The gas released during the reaction catches fire.
(ii) Calcium reacts with water less violently as compared to sodium.
(iii) Bubbles of hydrogen gas formed stick to the surface of calcium.

• A. Only (ii)
• B. (i) and (ii)
• C. (ii) and (iii)
• D. Only (i)

Answer 1

The correct option is C (ii) and (iii)

Option (d) is correct.

Unlike sodium, calcium does not undergo violent reaction with water. Though the reaction is exothermic, the heat evolved is not sufficient to cause an explosive reaction.

$\text{Ca(s)}+2{\text{H}}_2\text{O(l)}\to {\text{Ca(OH)}}_2\text{(aq)}+{\text{H}}_2\text{(g)}$

Calcium starts floating because the bubbles of hydrogen gas formed during the reaction stick to its surface and lifts it up.