Since pressure is connected to force, the force on a wall is
straightly proportional to the square of the velocity times the mass. The ratio
of the molecular weights of the CO2 and SO2 is (64.066 / 44.01) = 1.456. But,
we are not yet done. The actual rms velocity has to be taken as the square root
of that number, so the answer is 1.206.
