Is delta H a state function? My teacher says $H$ is a state function but $\Delta H$ is not. But I think both of them should be state function. Is he correct?
$\Delta H$ is a function of two states, the initial state and the final state.

For a given final state, there can be infinite $\Delta H$ values depending upon what the inital state was.  

For a given inital state, there can be infinite $\Delta H$ values depending upon what the final state is.

Therefore, $\Delta H$ is not a state function.