You are provided with the following PV diagram. The pressure is absolute pressure. The temperature at Y is 5 times the temperature at X. When moving from Y to X, does the gas gain or lose heat? Give a reason for your choice.

• A. Gain heat, ΔT is negative
• B. Lose heat, Work is done
• C. Lose heat, ΔT is negative
• D. Gain heat, Work is done

Answer: (C)