At $-20^{\circ} \mathrm{C}$ and $1 \mathrm{~atm}$ pressure, a cylinder is filled with equal number of $\mathrm{H}_2, \mathrm{I}_2$ and $\mathrm{HI}$ molecules for the reaction $$\mathrm{H}_2(\mathrm{~g})+\mathrm{I}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{HI}(\mathrm{g})$$, the $\mathrm{K}_{\mathrm{p}}$ for the process is $x \times 10^{-1}$. $\mathrm{x}=$$\underline{\hspace{2cm}}$. [Given : $$\mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$$]