In which of the following types of reactions is heat released to the environment?

• A. Endothermic reaction
• B. Electrolytic reaction
• C. Photochemical reaction
• D. Exothermic reaction

Answer: (D)

Verified step by step guidance

1. Understand the difference between endothermic and exothermic reactions: Endothermic reactions absorb heat from the surroundings, while exothermic reactions release heat to the surroundings.
2. Recognize that electrolytic reactions involve the use of electrical energy to drive a non-spontaneous chemical change, and they do not necessarily involve heat release to the environment.
3. Know that photochemical reactions are driven by light energy (photons) and may involve absorption of energy rather than release of heat.
4. Identify that the question asks for the type of reaction where heat is released to the environment, which corresponds to exothermic reactions.
5. Conclude that the correct classification for reactions releasing heat to the environment is exothermic reactions, as they transfer energy in the form of heat from the system to the surroundings.