a
(a) Halogen have \(-I\) and \(+M\) effect by which its electron delocalized in benzene ring by resonance & due to its \(-I\) effect its bonded with benzene ring and cannot be substitute by \(C{N^ - }\) & show the inertness against \(KCN\) while other option gives Aromatic nitrile

\(ArN_2^ + + CuCN \to ArCN + {N_2} + C{u^ + }\)

\(ArCON{H_2}\mathop {\xrightarrow{{{P_2}{O_5}}}}\limits_{ - {H_2}O} ArCN\)

\(ArCON{H_2} + SOC{l_2} \to ArCN + S{O_2} + 2HCl\)