We are tasked to solve for the volume of the gas that occupies when pressure and temperature changes to 400 Torr and 200 Kelvin from Torr and 400 Kelvin. We can use ideal gas law assuming constant gas composition and close system. The solution is shown below:
P1V1 / T1 = P2V2 / T2
V2 = P1V1T2 / T1P2
V2 = 800*72*200 / 400*400
V2 = 72 ml
The answer for the volume is 72 ml.
