Answer: Adiabatic.
- A Isothermal
- B Adiabatic
- C Isobaric
- D Isochoric
Correct answer: B. Adiabatic
Explanation: Adiabatic process: PV<sup>gamma</sup> = constant. Since gamma > 1, adiabatic curve is steeper than isothermal on P-V diagram.
The Carnot cycle alternates two isothermal steps (heat absorbed at TH, released at TC) with two adiabatic steps (no heat exchange); the enclosed loop area equals the net work output, and η = 1−TC/TH is the maximum possible efficiency between those two temperatures.
Concept context
Laws of thermodynamics, heat engines, entropy, and gas processes.