High-Yield Monocarboxylic Order

Decreasing Acidity Trend:

$$\text{HCOOH} > \text{C}_6\text{H}_5\text{COOH} > \text{CH}_3\text{COOH}$$

Concept: A standard target sequence for direct comparative questions in competitive exams. Formic acid leads because it lacks any electron-donating alkyl or aryl groups. Benzoic acid outpaces acetic acid because the $$sp^2$$ aromatic ring functions as a mild electron-withdrawing system relative to the purely donating ($$+I$$) methyl group of acetic acid.