Answer: Kelvin.
- A Celsius
- B Fahrenheit
- C Kelvin
- D Rankine
Correct answer: C. Kelvin
Explanation: The SI unit of temperature is Kelvin (K). Absolute zero = 0 K = -273.15 degrees Celsius.
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.