Question

A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains:
1. NaCl
2. HCl
3. LiCl
4. KCl

Answer 1

The eggshells contain ${\text{CaCO}}_3$ which on reacting with $\text{HCl}$ solution gives out a gas that turns lime-water milky.
The reaction can be represented as: ${\text{CaCO}}_3\left(s\right)+\text{2HCl(aq)}\to {\text{CaCl}}_2\left(aq\right)+{\text{H}}_2\text{O(l)}+{\text{CO}}_2\uparrow$