Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: For an endothermic chemical reaction, energy is absorbed as reactants are converted to products. Exothermic and endothermic reactions can be thought of as having energy as either a product of the reaction or a reactant. Exothermic reactions give off energy, so energy is a product. Endothermic reactions require energy, so energy is a reactant. Answer: endothermic
A:
Energy is absorbed as reactants are converted to products in what kind of chemical reaction?