Answer: 50%.
- A 25%
- B 50%
- C 75%
- D 100%
Correct answer: B. 50%
Explanation: Carnot efficiency = 1 - T<sub>cold</sub>/T<sub>hot</sub> = 1 - 300/600 = 1 - 0.5 = 50%.
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.