Alkaline hydrolysis of $1$ -bromo-$1$-phenylethane produce $1$-phenylethan-$1$-ol. The reaction proceed via $S _{ N } 1$ reaction. A carbocation is formed in the slow step of an $S_{N} 1$ reaction. The positively charged carbon of the carbocation intermediate is $s p^{2}$ - hybridised and the three bonds connected to an $s p^{2}$ - hybridised are in the same plane. Reaction involved is as follows:
