Final answer:
The statement is true; a system contains internal energy due to its kinetic and potential energies. Heat and work are not stored within a system but are processes of energy transfer between a system and its surroundings.
Step-by-step explanation:
The statement, "A system contains internal energy; it does not contain heat or work," is true. Internal energy (U) of a system is a measure of the energy contained in the system due to both the kinetic and potential energy of its molecules. It depends only on the state of the system, and not on how the system reached that state. In contrast, heat and work are forms of energy transfer between the system and its surroundings. Heat is energy that is transferred spontaneously due to a temperature difference, whereas work is the energy transferred when a force acts through a distance on the system.
Adding heat to a system or doing work on it will change its internal energy. However, we cannot say that a system contains heat or work as these are processes, not properties that a system can possess. This is an important distinction in thermodynamics and helps to explain phenomena such as phase changes, where heat transfer leads to changes in state without necessarily changing the temperature of a system.