Final answer:
A closed system is one that can exchange energy but not matter with its surroundings.
Step-by-step explanation:
The system that can exchange energy but not mass with its surroundings is a closed system. An example of a closed system is a sealed pouch of a ready-made dinner heated in boiling water; the pouch allows thermal energy to transfer from the boiling water without exchanging any matter unless it leaks. Conversely, an isolated system exchanges neither energy nor matter with its surroundings, but it's important to note that an ideal isolated system does not truly exist in reality. For instance, a thermos bottle is often considered an isolated system, but over time, it will still transfer heat to its environment.