For the reaction ${\mathrm{Fe}}_2\mathrm{N}\left(\mathrm{s}\right)+\frac{3}{2}{\mathrm{H}}_2\left(\mathrm{g}\right)\underset{ }{\rightleftharpoons }2\mathrm{Fe}\left(\mathrm{s}\right)+{\mathrm{NH}}_3\left(\mathrm{g}\right)$. The relation between Kc and Kp can be given as

$$\begin{gathered} {\mathrm{Fe}}_2{\mathrm{N}}_{\left(\mathrm{s}\right)}+\frac{3}{2}{{\mathrm{H}}_2}_{\left(\mathrm{g}\right)}\to 2{\mathrm{Fe}}_{\left(\mathrm{s}\right)}+{\mathrm{NH}}_{3\left(\mathrm{g}\right)} \\ \mathrm{\Delta ng}=\mathrm{no}. \mathrm{of} \mathrm{moles} \mathrm{of} \mathrm{gaseous} \mathrm{products} - \mathrm{no}. \mathrm{of} \mathrm{moles} \mathrm{of} \mathrm{gaseous} \mathrm{reactants} \end{gathered}$$

$=1-\frac{3}{2}$

$\begin{array}{l}{\mathrm{K}}_{\mathrm{p}}={\mathrm{K}}_{\mathrm{c}}{\left(\mathrm{RT}\right)}^{{\mathrm{\Delta n}}_{\mathrm{g}}}\\ \Rightarrow {\mathrm{K}}_{\mathrm{p}}={\mathrm{K}}_{\mathrm{c}}{\left(\mathrm{RT}\right)}^{\raisebox{1ex}{$-1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}\\ \Rightarrow {\mathrm{K}}_{\mathrm{c}}={\mathrm{K}}_{\mathrm{p}}{\left(\mathrm{RT}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}\end{array}$