Given $\left[{\mathrm{CS}}_2\right]=0.120\mathrm{M},\left[{\mathrm{H}}_2\right]=0.10\mathrm{M},\left[{\mathrm{H}}_2 \mathrm{S}\right]=0.20\mathrm{M}$ and $\left[{\mathrm{CH}}_4\right]=8.40\times {10}^{-5}\mathrm{M}$ for the following reaction at 900^o C, at eq. Calculate the equilibrium constant $\left({\mathrm{K}}_{\mathrm{c}}\right)$ ${\mathrm{CS}}_2\left(\mathrm{g}\right)+4{\mathrm{H}}_2\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{H}}_2 \mathrm{S}\left(\mathrm{g}\right)$