Answer: Temperature is constant.
- A Pressure is constant
- B Temperature is constant
- C Volume is constant
- D Heat is not exchanged
Correct answer: B. Temperature is constant
Explanation: Isothermal = constant temperature. For ideal gas: PV = constant (Boyle's law applies).
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.