Chemistry - Chemical Equilibrium Question with Solution | TestHub

A reaction system in equilibrium according to reaction $2{\mathrm{SO}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2{\mathrm{SO}}_3(\mathrm{g})$ in one litre vessel at a given temperature was found to be 0.12 mole each of ${\mathrm{SO}}_2$ and ${\mathrm{SO}}_3$ and 5 mole of ${\mathrm{O}}_2$. In another vessel of one litre contains 32 g of ${\mathrm{SO}}_2$ at the same temperature. What mass (in gm) of ${\mathrm{O}}_2$ must be added to this vessel in order that at equilibrium 20\% of ${\mathrm{SO}}_2$ is oxidized to ${\mathrm{SO}}_3$ ?