Final answer:
The incorrect statement about enthalpy is that a negative Enthalpy of reaction indicates an endothermic reaction; actually it signifies an exothermic reaction, where energy is released during bond formation.
Step-by-step explanation:
The statement that is not true about enthalpy is "C) If the Enthalpy of reaction is negative then it is an endothermic reaction." In fact, when the Enthalpy of reaction is negative, it indicates that the reaction is exothermic, meaning that energy is released to the surroundings.
During a chemical reaction, energy is required to break bonds, which implies that energy input is necessary, and therefore the enthalpy change for breaking bonds is always positive. Conversely, energy can be released when bonds are formed, as the system tends to become more stable, leading to a negative enthalpy change.
Thus, an exothermic reaction results when the total energy released from bond formation in the products exceeds the energy required to break bonds in the reactants. The negative enthalpy change (ΔH<0) reflects the excess energy released to the surroundings.