Question

What happens when calcium is treated with water?
(i) It does not react with water
(ii) It reacts violently with water
(iii) It reacts less violently with water
(iv) Bubbles of hydrogen gas formed stick to the surface of calcium

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

Answer 1

The correct option is D (iii) and (iv)

In general, metals form a metal oxide and hydrogen gas and this metal oxide when soluble in water dissolve further forming a metal hydroxide. But some metals form metal hydroxide directly.
In the case of calcium, the reaction with water is less violent and hydrogen starts floating on water and bubbles of hydrogen gas will stick to the metal surface.
$Ca+2H_{2}O\to Ca(OH{)}_2+H_2$