Question

The least acidic compound, among the following is:

• A. C
• B. D
• C. B
• D. A

Answer 1

Answer: (D)

A

Answer 2

Structure (A) is a benzene ring with an $\text{-OEt}$ group. It has no acidic hydrogen, whereas the other compounds have –OH (phenol), –SO₃H, or –COOH groups which are acidic.

(B) (phenol) has a moderate acidity (pKa ≈ 10).

(C) (benzene sulfonic acid) and (D) (carboxylic acid) are much more acidic.

Thus, the least acidic compound is (A).