ANS:A - the route/method through which final products are obtained.

The heat of reaction, also known as enthalpy change (Δ𝐻ΔH), refers to the heat energy absorbed or released during a chemical reaction. It represents the difference in enthalpy between the products and the reactants. Among the options provided:

• The route/method through which final products are obtained doesn't affect the heat of reaction. Enthalpy change is a state function, meaning it depends only on the initial and final states of the system, not on the path taken.
• The physical state of reactants and products does influence the heat of reaction. Different physical states can affect the reaction rate and the energy required to break or form bonds.
• Whether the reaction is carried out at constant temperature or constant pressure can affect the measured heat of reaction. Enthalpy change is usually measured under constant pressure conditions, but if the reaction involves a change in volume, then constant temperature conditions might be more appropriate.

• Heat of reaction is not influenced by the route/method through which final products are obtained.