Which of the following is a state function?

A state function is a property of a system that depends only on its current state and not on the path taken to reach that state. Energy, as a state function, includes various forms such as internal energy, enthalpy, and Gibbs free energy. The values of these energy forms depend only on the current conditions of the system (e.g., temperature, pressure, and composition), not on how the system reached those conditions.

In contrast, time and distance are not state functions because they describe how systems evolve or change over time or the measure of separation between two points, respectively. Additionally, the rate of reaction is a kinetic concept that refers to how quickly a reaction occurs, which is path-dependent; hence, it does not qualify as a state function.