Which of the following is an example of solid solution?

Amalgam of mercury with sodium

The correct answer is Option (4) → Amalgam of mercury with sodium

A solid solution is a homogeneous mixture where the solvent is solid. Amalgam is an alloy of mercury with another metal and behaves as a solid solution.

OPTION 1: Camphor in N₂ gas - This is a solid dissolved in gas. It is a gas solution, not a solid solution.

Option 2: Oxygen gas in water - Gas dissolved in liquid. This is a liquid solution.

Option 3: Ethanol in water - Liquid dissolved in liquid. This is also a liquid solution.

Option 4: Amalgam of mercury with sodium This is a metal dissolved in mercury forming an alloy. It behaves as a solid solution.