Assertion (A): Coupling of benzenediazonium chloride with phenol is done at pH 9-10 and not at pH 13-14. Reason (R): At very high pH the diazonium ion is converted to the unreactive diazotate ion, $C X_{6} H X_{5} N = N - O X^{-}$ . Choose the correct option.

Answer: A

Phenoxide formation needs alkali, so some alkalinity is required. But in strongly alkaline solution

ArN X_{2} X^{+}

is converted to

ArN = N - OH

and then to the diazotate ion, which is not an electrophile, so coupling fails. R therefore correctly explains why pH is held at 9-10.