Identify the pair of molecules that exhibit functional isomerism from the given options:

Step-by-step solution

Functional isomerism arises when two compounds have the same molecular formula but different functional groups. In option (A), CH ₃ CH ₂ CH ₂ CH ₂ OH and CH ₃ CH ( CH ₃) CH ₂ OH are both primary alcohols. They differ in the arrangement of the carbon chain, making them chain isomers. In option (B), CH ₃ CH ₂ COOH is a carboxylic acid and CH ₃ COOCH ₃ is an ester. Both have the same molecular formula C ₃ H ₆ O ₂ but possess different functional groups. Thus, they are functional isomers. In option (C), CH ₃ CH ₂ CH ₂