Question

A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains :

• A. KCl
• B. HCl
• C. NaCl
• D. LiCl

Answer 1

The correct option is B HCl

• The eggshells are made of calcium carbonate $\left(CaC{O}_3\right)$ and the gas that turns lime-water milky is carbon dioxide $\left(C{O}_2\right)$.
• When an acid reacts with calcium carbonate (or eggshells), then salt, carbon dioxide gas, and water $\left(H_{2}O\right)$ are formed. So, the solution must contain HCl (which is hydrochloric acid).
• The chemical equation for the reaction is as follows: $CaC{O}_3+2HCl\to CaC{l}_2+H_{2}O+C{O}_2$