Which of the following is true regarding the total energy of an isolated system?

The correct choice highlighting that the total energy remains constant in an isolated system is based on the principle of conservation of energy. In an isolated system, defined as one that does not exchange matter or energy with its surroundings, the total amount of energy is conserved over time. This means that although energy can change form—such as from kinetic to potential energy or vice versa—the sum total of energy in the system remains unchanged.

This principle is foundational in physics and chemistry and outlines how energy transformations occur without creating or destroying energy. For instance, in a closed system like a pendulum, while energy continuously shifts between kinetic and potential forms as it swings, the overall energy remains consistent.

In contrast, other choices are not aligned with this principle. The suggestion that total energy can change over time implies that energy could be created or destroyed, which contradicts the conservation law. Although energy can increase or decrease based on internal interactions, this is not applicable in an isolated context where no external energy is input or extracted. The idea that total energy increases indefinitely and that it depends on the state of matter also do not accurately reflect the conservation principle. Thus, the assertion that total energy remains constant in an isolated system is a valid and fundamental concept in the study of energy dynamics