Final answer:
The volume of gas in a rigid, constant volume container remains the same when more gas is added; instead, the pressure increases due to the fixed size of the container and the unchanging temperature.
Step-by-step explanation:
The student's question is related to the behavior of gases in a rigid container with a constant volume.
When gas is added to a rigid container, the volume of the gas cannot increase because the container does not expand or contract. According to Avogadro's Law, under constant temperature, the volume occupied by a gas is directly proportional to the number of moles of gas present. However, in a rigid container, since volume cannot change, adding more gas increases the number of molecules inside the container, leading to a rise in pressure.
This phenomenon can also be described by the Ideal Gas Law, which states that the product of pressure (P) and volume (V) is proportional to the number of moles (n) and the temperature (T), P*V = n*R*T, where 'R' is the ideal gas constant. Since the volume and temperature remain constant in this situation, the increase in the number of moles causes an increase in pressure.
In summary, the volume of gas in a rigid container remains constant when more gas is added because the container's size is fixed, resulting in increased pressure.