$\mathop { - CH{{(C{H_3})}_2}}\limits_1 \,\,\,\,\,\,\,\,\,\,\,\mathop { - C{H_2}C{H_2}Br}\limits_2 \,\,\,\,\,\,\,\,\,\,\mathop { - C{H_2}Br}\limits_3 \,\,\,\,\,\,\,\,\,\,\mathop { - C{{(C{H_3})}_3}}\limits_4 $
$I = II = III = IV$
$\begin{array}{*{20}{c}}
{O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3} - C{H_2} - C - C{H_2} - C{H_2} - C{H_3}}
\end{array}$