Concept:Boiling point is heavily dependent on the strength of intermolecular forces. Hydrogen bonding is exceptionally strong in carboxylic acids because they form dimers.
Solution:- Ethers (Option C) and tertiary amines (Option D) lack \( \text{O-H} \) or \( \text{N-H} \) bonds and cannot act as hydrogen bond donors; their boiling points are low.
- Alcohols like ethanol (Option B) can hydrogen bond, but only single strands.
- Carboxylic acids like acetic acid (Option A) form tightly bound cyclic dimers via double hydrogen bonds, drastically increasing the energy required to vaporize them.
Why other options are incorrect:None of the other functional groups can form the uniquely stable cyclic dimer geometry characteristic of carboxylic acids.
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