Which of the following is an example of a state function?

A state function is a property of a system that depends only on its current state, regardless of how it arrived at that state. It is characteristic of the system's state, and its value is not influenced by the path taken to reach that state. Examples of state functions include properties like temperature, pressure, volume, enthalpy, internal energy, and entropy.

Entropy is a measure of the disorder or randomness in a system, and it quantifies the number of microstates corresponding to a macrostate. The value of entropy at any given moment depends solely on the state of the system (for example, its temperature and volume) and does not depend on how the system reached that state.

In contrast, work done on a system, the change in temperature during a process, and energy input into a reaction are all path functions. They depend on the specific process or path taken to change the system's state. Therefore, since entropy meets the criteria of a state function by being dependent only on the current state of the system, it is the correct choice.