$\begin{array}{*{20}{c}}
{C{H_3}C{H_2}CH - C{H_2}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Br\,\,\,\,\,\,\,\,\,Br\,\,}
\end{array}\xrightarrow[\begin{subarray}{l}
(ii)\,NaN{H_2} \\
in\,liq.\,N{H_3}
\end{subarray} ]{{(i)\,KOH\,alc.}}$
$(i)$ $C{H_3} - C \equiv C - C{H_3}$
$(ii)$ $C{H_3} - C{H_2} - C{H_2} - C{H_3}$
$(iii)$ $C{H_3} - C{H_2} - C \equiv CH$
$(iv)$ $C{H_3} - CH = C{H_2}$