MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The acidic strength of carboxylic acids depends on the stability of the conjugate base (carboxylate ion). Electron-withdrawing groups (EWG) stabilize the conjugate base through the -I effect, thereby increasing the acidic strength. Electron-donating groups (EDG) destabilize the conjugate base through the +I effect, decreasing the acidic strength. In the given options: ClCH _2 COOH has a - Cl group which exerts a strong -I effect. HCOOH has a hydrogen atom (reference for I effect). CH _3 COOH has a - CH _3 group which exerts a +I effect. CH _3 CH _2 COOH has an ethyl group which exerts a stronger +I effect than the methyl group. Due to the strong -I effect of the chlorine atom, the chloroacetate ion is the most stable conjugate base. Thus, ClCH _2 COOH is the strongest acid. Answer: ClCH _2 COOH