What type of system exchanges energy but not matter with its surroundings?

The correct choice is a closed system, which is characterized by the ability to exchange energy with its surroundings while preventing the transfer of matter. In such a system, energy can transfer in forms such as heat or work, allowing for changes in temperature and pressure, among other things. As a result, the internal processes can occur without any material entering or leaving the system.

For example, consider a sealed container of gas that allows heat to be added or removed but does not permit the gas itself to escape or any other material to enter. The pressure and temperature of the gas can be influenced by external energy input without changing the mass of the system.

The other types of systems differ in their interactions with their surroundings. An open system can exchange both energy and matter, while an isolated system does not exchange either. A mixed system is not a standard classification in thermodynamics and does not effectively describe a specific system type.