Phenol reacts with a compound (X) in the presence of aq. NaOH to produce phenyl benzoate. Identify (X). 

Benzoyl chloride 

The correct answer is option 2. Benzoyl chloride.

Phenol reacts with a compound $X$ in the presence of aqueous NaOH to produce phenyl benzoate. This reaction is a typical example of the Schotten-Baumann reaction, which involves the formation of an ester from a phenol and an acid chloride.

Schotten-Baumann Reaction Mechanism:

Phenol Deprotonation:

Phenol $(C_6H_5OH)$ is deprotonated by aqueous NaOH to form the phenoxide ion $(C_6H_5O^-)$

Nucleophilic Attack:

The phenoxide ion then acts as a nucleophile and attacks the carbonyl carbon of benzoyl chloride $(C_6H_5COCl)$, which is an acyl chloride. This leads to the formation of phenyl benzoate and hydrochloric acid $(HCl)$.

The compound $X$ that reacts with phenol in the presence of aqueous NaOH to produce phenyl benzoate is benzoyl chloride. Thus, the correct answer is Benzoyl chloride.