Phenol on oxidation with chromic acid gives

The correct answer is option 4. Benzoquinone.

Let us go into detail on the oxidation of phenol with chromic acid.

When phenol undergoes oxidation with chromic acid \((Na_2Cr_2O_4)\), it undergoes a benzylic oxidation process. The benzylic position in phenol refers to the carbon atom adjacent to the aromatic ring, which is the position where the hydroxyl group \((-OH)\) is attached.

The reaction involves the removal of a hydrogen atom from the benzylic position and the addition of an oxygen atom, resulting in the formation of a carbonyl group. The reaction can be represented as follows:


The product formed is benzoquinone, which is a compound with a quinone structure, characterized by a cyclic arrangement of carbonyl groups. In the case of phenol oxidation, benzoquinone is specifically formed due to the benzylic oxidation process.