Which carboxylic acid has a rancid butter-like smell?
The PDF notes mention that butanoic acid (CH₃CH₂CH₂COOH) has a characteristic rancid butter-like odor.
Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids