Fundamentholfundamenthol

JEE Advanced 2025 Paper 1, Chemistry Section 1 Q4: Aromatic Hydrocarbons: Benzene

JEE Advanced2025Paper 1Chemistry Section 1
Q.

Consider the depicted hydrogen (H) in the hydrocarbons given below. The most acidic hydrogen (H) is

  1. A

  2. B
  3. C
  4. D
Solution

Acidity is determined by the stability of the conjugate base. Removal of the marked H in structure (B) places the resulting carbanion on a carbon attached to the cyclopentadiene ring. Delocalisation pushes the negative charge into the ring, completing an aromatic six -electron system (cyclopentadienide-like).

The conjugate bases from the other structures are not aromatic and have no comparable stabilisation.

Structure (B) provides the most acidic H. Option (B).

Concept behind this question

Aromatic Hydrocarbons: Benzene Notes, formulas and examples →

More previous year questions on Aromatic Hydrocarbons: Benzene

Practice more Chemistry Section 1

Concept-wise practice with instant solutions on Fundamenthol.

Start practicing →