If the temperature decreases during a process, the reaction is

If the temperature decreases during a process, the reaction is

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

Answer: (A)

Heat flowing into the system makes the surroundings cool. When a process is endothermic, the system absorbs heat from its surroundings, so the temperature of the surroundings drops. That’s why a decrease in temperature indicates endothermic behavior. If the temperature stayed the same, it would be isothermal. If no heat could enter or leave, it would be adiabatic. If heat were released to the surroundings, the surroundings would warm up, which is the opposite of what’s described. Exothermic processes release heat, not absorb it.

Heat flowing into the system makes the surroundings cool. When a process is endothermic, the system absorbs heat from its surroundings, so the temperature of the surroundings drops. That’s why a decrease in temperature indicates endothermic behavior.

If the temperature stayed the same, it would be isothermal. If no heat could enter or leave, it would be adiabatic. If heat were released to the surroundings, the surroundings would warm up, which is the opposite of what’s described. Exothermic processes release heat, not absorb it.