$\mathrm{PCl}_5(\mathrm{~g}) \rightarrow \mathrm{PCl}_3(\mathrm{~g})+\mathrm{Cl}_2(\mathrm{~g})$ In the above first order reaction the concentration of $\mathrm{PCl}_5$ reduces from initial concentration $50 \mathrm{~mol} \mathrm{~L}^{-1}$ to $10 \mathrm{~mol} \mathrm{~L}^{-1}$ in $120 \mathrm{minutes}^2$ at 300 K . The rate constant for the reaction at 300 K is $x \times 10^{-2} \mathrm{~min}^{-1}$. The value of $x$ is $\_\_\_\_$ [Given $\log 5=0.6989$