a
(a) \(C{H_2} = C{H_2} + H\mathop O\limits^ - \mathop {Cl}\limits^ + \to \) \(\mathop {\begin{array}{*{20}{c}}
{\mathop C\limits^2 {H_2} - \mathop C\limits^1 {H_2}} \\
{\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,} \\
{\,OH\,\,\,\,\,\,\,\,Cl\,\,\,\,\,\,\,\,\,}
\end{array}}\limits_{1 - Chloro - 2 - hydroxyethane} \)