Benzoic acid is almost insoluble in which of the following solvents?

The correct answer is option 3. Cold water.

Why Benzoic Acid Hates Cold Water

Benzoic acid ($C_6H_5COOH$) consists of two main parts:

1. The Benzene Ring ($C_6H_5$): This is a large, non-polar hydrocarbon group that is "hydrophobic" (water-fearing).
2. The Carboxyl Group ($-COOH$): This part is polar and can form hydrogen bonds with water.

In cold water, the large non-polar benzene ring dominates the molecule's behavior. The water molecules would rather stay hydrogen-bonded to each other than break apart to surround the bulky, non-polar ring. This makes the acid almost insoluble at room temperature or below.

Comparison with Other Solvents

Solvent	Solubility Level	Reason
Ether	High	Both are organic and share similar intermolecular forces.
Alcohol	High	Ethanol has a non-polar tail that interacts well with the benzene ring.
Benzene	High	Non-polar dissolves non-polar; they are structurally very similar.
Hot Water	Moderate	As temperature increases, kinetic energy helps break the intermolecular bonds, allowing it to dissolve better than in cold water.

Summary

Benzoic acid prefers organic solvents (like options 1, 2, and 4) because it is largely non-polar.