Which statement best defines an endothermic reaction?

• A. Involves no temperature change
• B. Produces light
• C. Absorbs energy from surroundings
• D. Releases energy to surroundings

Answer: (C)

Endothermic reactions absorb energy from their surroundings. In these reactions, heat (or energy) flows into the system, so the surroundings often feel cooler as the reaction takes in energy to drive bond-breaking and bond-forming processes. The statement that best defines this is the one describing energy being absorbed from the surroundings, because that captures the essential energy flow of the process.

It’s not about producing light or necessarily having no temperature change. A reaction that releases energy to the surroundings would be exothermic, not endothermic. And while some endothermic changes can show small or hard-to-detect temperature changes in the surroundings, the defining feature is the inward transfer of energy. For example, dissolving certain salts in water draws energy from the surroundings, causing a cooling effect.