Chemistry - Halogen Derivative Question with Solution | TestHub

$\begin{array}{ccccccc}{\text{C}}_2{\text{H}}_5\text{Cl}& +& \text{AgCN}& \to & {\text{C}}_2{\text{H}}_5\text{NC}& +\text{AgCl}& \\ & & & & \left(\text{X}\right)& & \end{array}$

Thus, X is ethyl isocyanide. As the question is asking about the functional isomer of X, the functional isomer of C₂H₅NC will be C₂H₅CN, i.e. ethyl cyanide.