What is the behavior of internal energy change (ΔE) and mass change (ΔM) in a closed system?

In a closed system, the behavior of internal energy change (ΔE) and mass change (ΔM) can be understood through the principles of thermodynamics and the law of conservation of mass.

The internal energy (ΔE) of a closed system can change due to various processes such as heat transfer and work done on or by the system. For instance, if work is done on the system or if the system absorbs heat, the internal energy increases. Conversely, if the system does work on its surroundings or releases heat, the internal energy decreases. Therefore, it is accurate to state that internal energy can vary in a closed system.

On the other hand, when considering mass change (ΔM), a closed system does not exchange matter with its surroundings. Consequently, the total mass of the system remains constant over time. Thus, while the internal energy can fluctuate depending on the system's activity, mass does not change because no matter can enter or leave the system.

This is why the correct understanding is that internal energy change does occur (ΔE: Yes) while mass change does not occur (ΔM: No) in a closed system.