
$HC\, \equiv \,CH\,\xrightarrow[{20\% \,{H_2}S{O_4}}]{{1\% \,HgS{O_4}}}A$ $\xrightarrow[{{H_2}O}]{{C{H_3}MgX}}B\xrightarrow{{[O]}}(C)$

${H_2}C\, - \,\,\mathop C\limits_{\mathop |\limits_D } H\, - \,\,\mathop C\limits_{\mathop |\limits_{C{H_3}} } H\, - \,\,C{H_3}\, + \,\,Br\,\, \to \,\,'X'\,\, + \,\,HBr$
