b
\(\mathop {C{H_3} - C \equiv N}\limits_{ethane\,\,nitrile} \) \(+\) \(RMgX\) \(\to \) \({\begin{array}{*{20}{c}}
  {C{H_3} - C = N - RMgX} \\ 
  {|{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \,\,\,\,\,\,\,\,\,\,\,\,\,{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} } \\ 
  {R\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} } 
\end{array}}\) \(\xrightarrow {H_2O}\)  \(\mathop {\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,O} \\ 
  {\,\,\,\,\,\,\,\,\,||} \\ 
  {RC{H_3} - C - R} 
\end{array}}\limits_{(ketone)} \) \(+\) \(NH_3\) \(+\) \(Mg(OH)X\)