Distinguish between endothermic and exothermic processes.

• A. Endothermic processes absorb heat; exothermic processes release heat.
• B. Endothermic processes release heat; exothermic processes absorb heat.
• C. Endothermic processes involve chemical reactions only.
• D. Endothermic and exothermic are the same.

Answer: (A)

Heat flow direction distinguishes these two ideas. In endothermic processes, the system must absorb energy from the surroundings, so heat moves into the system and the surroundings cool down. In exothermic processes, energy is released by the system as heat to the surroundings, making the surroundings warmer. Think of melting ice or evaporating water as endothermic because they draw in heat, while burning fuel or a chemical reaction that lights a fire is exothermic because heat is given off. The statement that endothermic processes absorb heat and exothermic processes release heat captures this directional energy transfer.