State Hess's law of constant heat summation.

here's the solution to the question:

Hess's law of constant heat summation states that the total enthalpy change for a chemical reaction is the same, regardless of the pathway or the number of steps taken, provided the initial and final conditions (temperature, pressure, and states of matter) are the same. It is a direct consequence of the first law of thermodynamics, as enthalpy is a state function.