${CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{Br} \xrightarrow[\Delta]{\mathrm{KOH}_{(a k)}} \mathrm{A} \xrightarrow{\mathrm{HBr}} \mathrm{B} \xrightarrow[\mathrm{KOH}_{(a) i}]{\Delta} \mathrm{C}$
$(1)$ $\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\, \\
{{H}_{3}}C-C-C{{H}_{2}}-Cl \\
\end{matrix}$
$(2)$ ${{H}_{2}}C-C{{H}_{2}}-C{{H}_{2}}-Cl$
$(3)$ ${{({{H}_{3}}C)}_{3}}C-Cl$