Step 1: Identify the reaction type (azo coupling). The equation involves benzene diazonium chloride ($C_6H_5N_2^+Cl^-$) reacting with phenol in alkaline medium. This is an azo coupling reaction, a type of electrophilic aromatic substitution in which the diazonium ion acts as the electrophile. Step 2: Role of the alkaline medium. Alkali ($OH^-$) converts phenol to the phenoxide ion ($C_6H_5O^-$), which is more electron-rich at ortho and para positions. This activates the ring toward the weakly electrophilic diazonium ion. Step 3: Product and azo linkage formed. Coupling occurs at the para position (less sterically hindered), forming the azo linkage $-N{=}N-$. The product is p-hydroxyazobenzene, an orange-yellow azo dye: $C_6H_5{-}N{=}N{-}C_6H_4{-}OH$. Overall: $C_6H_5N_2^+Cl^- + C_6H_5OH \xrightarrow{OH^-} C_6H_5{-}N{=}N{-}C_6H_4{-}OH + HCl$.
