A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains
Explanation
Option (B) HCl is correct. Crushed egg-shells are made of calcium carbonate. According to the context, all metal carbonates react with acids to give a corresponding salt, carbon dioxide and water. Among the given options, only HCl (hydrochloric acid) is an acid. The other options—NaCl, LiCl, and KCl—are salts and will not react with calcium carbonate to produce carbon dioxide gas. When carbon dioxide gas is passed through lime water, it turns milky due to the formation of calcium carbonate as a white precipitate: Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l).
Solution Steps
Step 1: Identify that egg-shells contain calcium carbonate (a metal carbonate).
Step 2: Recall that metal carbonates react with acids to produce carbon dioxide gas.
Step 3: Identify that HCl is the only acid among the given options (NaCl, LiCl, KCl are salts).
Step 4: Confirm that CO2 turns lime-water milky, forming CaCO3 precipitate.