$PCl_{5}\rightleftharpoons PCl_{3}+PCl_{2}$
if the equilibrium constant $(K_{C})$ for the above reaction at 500 K is 1.79 and the equilibrium concentration of $PCl_{5}$ and $PCl_{3}$ are 1.41 M and 1.59 M . respectively , then the concentration of $Cl_{2}$ is approximately