Identify which are not the state functions among the following:

Enthalpy is a state function because it depends only on two thermodynamic properties of the state the substance is at the moment (like temperature and pressure, or temperature and entropy, or any pair of other state functions). It does not depend on the path followed by the substance to get there.It follows that an enthalpy change is a difference between two values of a state function. Thus, it depends on a total of 4 state variables (2 marking the initial state and 2 more marking the final state). As a result, an enthalpy change is NOT a state function.