Question

Lime water turnswhen CO2 is passed through it.

• A. milky
• B. red
• C. blue

Answer 1

The correct option is A milky

Lime water is calcium hydroxide solution (${\text{Ca(OH)}}_2$) and it is a base. Carbon dioxide (${\text{CO}}_2$) being a non-metallic oxide (acidic in nature), reacts with the calcium hydroxide to form a salt called calcium carbonate.
Calcium carbonate is white and insoluble in water, hence it makes lime water appear milky.
The reaction is given below:
${\text{Ca(OH)}}_2\text{(aq)}+{\text{CO}}_2\text{(g)}\to {\text{CaCO}}_3\text{(s)}+{\text{H}}_2\text{O}\text{(l)}$