$(I) \,C{H_3}CH = C{H_2} + HBr\xrightarrow{{peroxide}}$
$(II)\, C{H_3}CH = C{H_2} + HBr\xrightarrow{{CC{l_4}}}$
$(III)\, C{H_3}C{H_2}C{H_3} + B{r_2}\xrightarrow{{hv}}$
$(IV)\,C{H_3}CH = C{H_2} + B{r_2}\xrightarrow{{CC{l_4}}}$
$\begin{matrix}
CH-C{{O}_{2}}H \\
\,||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
CH-C{{O}_{2}}H \\
\end{matrix}\xrightarrow[(two\,mole)]{NaOH}(A)\xrightarrow{electrolysis}(B);$