In the reaction, $$\mathrm{H}_2+\mathrm{I}_2 \rightleftharpoons 2 \mathrm{HI}$$. In a 4L flask, 0.8 mole of each $$\mathrm{H}_2$$ and $$\mathrm{I}_2$$ are taken. All equilibrium, 1 mole of $$\mathrm{HI}$$ is formed. What will be the value of equilibrium constant $$K_C$$ ?