Chemistry - GOC Question with Solution | TestHub
How many of the following is stronger acid than benzoic acid
Answer:
Solution:
Compound (i) p-chlorobenzoic acid: The chloro group (–Cl) acts as an electron-withdrawing group via its inductive effect (–I), stabilizing the carboxylate ion and making it a stronger acid than benzoic acid.
Compound (ii) o-isopropylbenzoic acid: Due to the ortho-effect, any ortho-substituted benzoic acid is generally a stronger acid than benzoic acid itself because steric hindrance forces the –COOH group out of the benzene ring's plane, preventing destabilizing resonance.
Compound (v) p-nitrobenzoic acid: The nitro group (–NO₂) is a powerful electron-withdrawing group by both resonance (–M) and inductive (–I) effects, significantly stabilizing the conjugate base and increasing acidity.
Compounds (iii) and (iv): Carbonic acid (H₂CO₃) and phenol (C₆H₅OH) are both inherently weaker acids than benzoic acid.
Therefore, exactly 3 compounds [(i), (ii), and (v)] are stronger acids than benzoic acid.
