What is an isolated system?

An isolated system is defined as one that can exchange neither energy nor matter with its surroundings. This means that all components and energy within the system remain constant over time, as nothing from outside can enter the system and nothing can escape from it. In physical science, this concept helps in studying the conservation of energy and mass, as isolated systems maintain a fixed total amount of both energy and matter.

The other choices focus on different types of systems. For instance, a system that can exchange energy but not matter is known as a closed system. A system where matter can enter and leave freely would be considered an open system. The option that mentions the system only losing energy does not appropriately capture the essence of isolation since it implies a change rather than a complete lack of exchange. Thus, the definition of an isolated system is clear and fundamental to understanding thermodynamic principles and the behavior of systems in physics.