A reaction that warms the surroundings is described as

• A. Exothermic
• B. Endothermic
• C. Isothermal
• D. Adiabatic

Answer: (A)

When a reaction warms the surroundings, heat is being released from the reacting system into the surroundings. That is the defining feature of an exothermic process. The system loses energy as heat, so the surroundings gain energy, often seen as an increase in temperature.

Endothermic would involve heat entering the system, not leaving it, so the surroundings would tend to cool. Isothermal describes a process where the temperature remains constant, which isn’t implied by simply warming the surroundings. Adiabatic means no heat exchanges with the surroundings at all, so there wouldn’t be warming of the surroundings.