Answer: kelvin.
- A kelvin
- B degree celsius
- C fahrenheit
- D joule
Correct answer: A. kelvin
Explanation: The kelvin (K) is the SI base unit of temperature.
During a phase change (melting or boiling), temperature stays constant while heat is absorbed entirely as latent heat (Q=mL); temperature only rises again once the substance is fully in its new phase.
Concept context
Temperature scales, thermal expansion, calorimetry, and the three modes of heat transfer including radiation laws.