c
(c) \(C{H_3} - C{H_2} - Br + \mathop {KOH}\limits_{{\rm{alk}}}\,\,  \xrightarrow{Dehydrohal ogenation}  \,\,C{H_2} = C{H_2} + KBr + {H_2}O\)

In alcoholic \(KOH\) alkoxide ions \((R{O^ - })\) are present which is a strong base. They abstract proton from ?-carbon of alkyl halide and favours elimination reaction

\(\mathop {ROH}\limits_{{\rm{Alcohol}}} + KOH \to \mathop {ROK + {H_2}O}\limits_{{\rm{Potassium \,alkoxide}}} \)

\(ROK \to \mathop {R{O^ - }}\limits_{{\rm{Alkoxide \,ion}}} + {K^ + }\)

\(R{O^ - } + H - \mathop {C{H_2}}\limits^\beta - \mathop {C{H_2}}\limits^\alpha - Br \to ROH + C{H_2} = C{H_2} + Br\)