Which statement best defines an exothermic reaction?

• A. Absorbs energy from surroundings
• B. Does not involve energy transfer
• C. Releases energy to surroundings
• D. Only occurs at high temperatures

Answer: (C)

Exothermic reactions release energy to the surroundings. In these reactions the energy content of the products is lower than that of the reactants, so the excess energy is transferred out as heat (and sometimes light), which is why things feel warmer after the reaction, like when a fuel burns or a neutralization gives off heat. The defining idea is this energy flow outward to the surroundings.

That makes the statement about releasing energy to the surroundings the best description. The other ideas aren’t correct: absorbing energy from the surroundings would describe an endothermic process; saying there’s no energy transfer contradicts the basic energy change; and claiming it only happens at high temperatures isn’t true for exothermic reactions.