A vessel (volume 8.2 L) contains H2(g) at 2 atm. pressure. When H2S(g) at a pressure of 4 atm. is introduced into the vessel the reaction $8{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)\rightleftharpoons 8{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{S}}_8\left(\mathrm{s}\right)$occurs at a temperature of 2000 K.

It is found that ${\left[\frac{\mathrm{n}\left({\mathrm{H}}_2\right)}{\mathrm{n}\left({\mathrm{H}}_2\mathrm{S}\right)}\right]}_{at equilibrium}={\left[\frac{\mathrm{n}\left({\mathrm{H}}_2\mathrm{S}\right)}{\mathrm{n}\left({\mathrm{H}}_2\right)}\right]}_{at t=0}$