$(a)$ $CH_3CH_2CH_2CH_2Br$
$(b)$ $\begin{matrix} \begin{matrix} \,\,\,\,\,\,C{{H}_{3}} \\ | \\ \end{matrix} \\ {{H}_{3}}C-C-C{{H}_{3}} \\ | \\ \,\,Br \\ \end{matrix}$
$(c)$
$\begin{array}{*{20}{c}} {C{H_3}\,\,\,} \\ {|\,\,\,\,\,\,\,\,} \\ {C{H_3} - C - CHC{H_3}} \\ {\,|\,\,\,\,\,\,\,\,\,\,|} \\ {\,\,H\,\,\,\,\,\,\,Br} \end{array}$ $\xrightarrow{{C{H_3}OH}}$