X-CH2COOH, acidic strength will be less than CH3COOH if X is

EWG increase the acidic strength of aliphatic carboxylic acids by-I effect.—I effect of —CF3>—NO2>—CN>—F>—Cl>—Br>—I>—PhEDG decrease the acidic strength of aliphatic carboxylic acids by +I effectAlkyl groups shows +I effect;+I effect increase with increase in chain length and bulkiness of alkyl group.∴ Acidic strength of O2N−CH2−COOH>NC−CH2−COOH>F−CH2−COOH>CH3−COOH>R−CH2−COOH