Two chemicals react in an endothermic reaction. What can be known about this reaction?

An endothermic reaction takes in heat from its surroundings, so heat is absorbed. This happens when breaking bonds in the reactants requires more energy than forming bonds in the products releases; choice A describes that energy imbalance. The reaction being endothermic does not by itself mean a precipitate or gas must form.

AI-written and checked against the verified answer.