An oxidation of phenol with chromic acid produces

Benzoquinone

The correct answer is Option (4) → Benzoquinone

Oxidation of Phenol

Phenol ($\text{C}_6\text{H}_5\text{OH}$) is easily oxidized due to the presence of the activating hydroxyl group ($\text{-OH}$).

• Reagent: Chromic acid ($\text{H}_2\text{CrO}_4$) is a strong oxidizing agent, often generated in situ from sodium dichromate ($\text{Na}_2\text{Cr}_2\text{O}_7$) or potassium dichromate ($\text{K}_2\text{Cr}_2\text{O}_7$) in acidic medium ($\text{H}_2\text{SO}_4$).
• Reaction: When phenol is treated with chromic acid, it undergoes oxidation to form 1,4-Benzoquinone (or simply p-Benzoquinone).

The reaction converts the aromatic ring system into a non-aromatic, cyclic dione structure. This is the characteristic product when strong oxidizing agents are used under these conditions.

The correct option is: Benzoquinone