Step-by-step explanation:
According to ideal gas equation, product of pressure and volume equals n times R times T.
Mathematically, PV = nRT
where P = pressure
V = volume
n = number of moles
R = gas constant
T = temperature
Therefore, it can be seen that volume is directly proportional to number of moles. Hence, when there is decrease in number of moles that is, decrease in the amount of gas then there will be decrease in volume also.
Thus, we can conclude that if the amount of gas is decreased and the temperature and pressure stay constant then it there will be decrease in its volume.