rigid container of fixed volume holds 0.10 mol of CH4(g) and 0.20 mol of Ar(g), with a total pressure of 600 Torr.

rigid container of fixed volume holds 0.10 mol of CH4(g) and 0.20 mol of Ar(g), with a total pressure of 600 Torr. What amount of Ar(g) must be added to the container to increase the total pressure to 900 Torr?