a
\((a)\) \(C{H_3} - C{H_2} - C \equiv CH\mathop {\xrightarrow{{HgS{O_4},{{60}^o}C}}}\limits_{{H_2}S{O_4}} \) \(\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,O} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,||} \\
{C{H_3} - C{H_2} - C - C{H_3}}
\end{array}\)