B. It represents the change in enthalpy for the reaction.
Explanation:
The potential energy diagram for a chemical reaction shows its potential energy plotted against the reaction progress coordinate. The potential energy diagram shows how the potential energy of reactants and products vary as reactants are converted into products.
The potential energy of the system refers to energy stored in the chemical bonds of reactants and products. The difference between the potential energy of reactants and products is known as the enthalpy of reaction. This difference in potential energy may be positive or negative. A positive difference in potential energy implies an endothermic reaction while a negative difference in potential energy implies an exothermic reaction.
