In which thermodynamic process does the volume of a gas remain constant?

The process in which the volume of a gas remains constant is known as an isochoric process. During this process, since there is no change in volume, any heat transfer that occurs results in a change in pressure and temperature of the gas instead.

In a practical context, this means that if heat is added to a gas at constant volume, the internal energy of the gas increases, which in turn raises its temperature and possibly its pressure, depending on the specific conditions. This is significant in various engineering applications, such as in closed containers where gases are heated or cooled without any possibility for expansion or compression.

The other processes involve different characteristics: an isothermal process keeps the temperature constant while allowing volume to change, an adiabatic process involves no heat transfer and can result in changes in both temperature and pressure with volume change, and an isobaric process maintains constant pressure but allows for changes in volume and temperature. Each of these processes illustrates different behaviors of gases under specific conditions, highlighting the unique nature of the isochoric process.