At -20 °C and 1 atm pressure, a cylinder is filled with equal number of H_2, I_2 and HI molecules for the reaction H_2( g )+ I_2( g ) ⇌ 2 HI ( g ),…

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