What describes an endothermic reaction?

• A. Absorbs energy from the surroundings, causing temperature to decrease.
• B. Releases energy as heat.
• C. Occurs with no energy change.
• D. Only happens in cold conditions.

Answer: (A)

Endothermic reactions take in energy from their surroundings, so the immediate effect is cooling the surroundings. When heat flows into the system, the surrounding environment loses heat, and its temperature drops if no heat source replaces it. This is why some processes feel cold, like when certain salts dissolve or in photosynthesis, which uses light energy to drive the reaction.

The description given—absorbing energy from the surroundings, causing a temperature decrease—fits this idea exactly. The other statements describe different scenarios: releasing energy as heat happens in exothermic reactions; no energy change would mean no heat transfer at all, which isn’t characteristic of a typical chemical reaction; and endothermic reactions aren’t limited to cold conditions—they can occur at a range of ambient temperatures depending on the system.