Which of the following reactions emits energy or heat in the products?

The appropriate choice for the reaction that emits energy or heat in the products is the exothermic reaction. In an exothermic reaction, energy is released to the surroundings, often in the form of heat, resulting in a temperature increase in the environment surrounding the reacting substances. This release of energy occurs because the total energy of the products is lower than that of the reactants after the reaction has taken place, indicating that energy has been released during the process.

In contrast, endothermic reactions absorb energy from their surroundings, leading to a decrease in temperature in the environment, as these reactions require energy input to proceed. Hydrolysis reactions involve the breakdown of compounds through the interaction with water and do not specifically categorize energy emission or absorption. Synthesis reactions combine simpler substances to form a more complex product and can be either exothermic or endothermic, depending on the specific reactants involved. However, they do not inherently imply energy release without additional context.