What does an isothermal process involve?

An isothermal process is characterized by maintaining a constant temperature throughout the entire process. This means that, regardless of the energy exchange that occurs (typically in the form of heat), the temperature of the system does not change. In thermodynamics, isothermal processes are often examined in the context of ideal gases, where the relationship between pressure, volume, and temperature is described by the ideal gas law.

During an isothermal process, the internal energy of an ideal gas remains constant since it is solely a function of temperature. As a result, any heat added to the system will do work, and any work done on the system will release heat, ensuring the temperature stays the same. This principle has significant implications in both theoretical contexts and practical applications, such as in heat engines and refrigerants.

The other choices pertain to different thermodynamic processes. For instance, constant pressure defines an isobaric process, while constant volume refers to an isochoric process. Constant mass doesn't directly correspond to the definition of a thermodynamic process in terms of energy exchanges and is more of a general condition for many types of processes. These distinctions help clarify the unique characteristics of an isothermal process in thermodynamic systems.