Question: in the neutralisation, the enthalpy is lower for the products than it is for the reactants, identify the effect of this on the heat of the reaction.
Not 100% sure what this question is asking but i'll have a go.
Neutralization reactions are exothermic, meaning they release heat as the reaction proceeds. Enthalpy describes the amount of energy a compound contains. The fact that the reaction is exothermic means that the enthalpy of products is less than reactants due to energy being released as heat into the environment. I'm not sure how this has an "effect" on the heat of reaction. All that can be said is that the heat of reaction (delta H) is negative because the reaction is exothermic.