Question

Which describes the enthalpy change associated with an endothermic reaction?

Answer 1

This is an activation energy graph of an endothermic reaction. it goes up and then comes back down a little but stabilizes out at a point above where it started. This is because the products have more energy than the reactants because you had to put energy into it to make it go.

During an endothermic reaction you add energy to make it go. Whenever you put energy into something that enthalpy change is positive. Looking at the graph, we can conclude that the reactants have less energy than the products. Answer is number two.