Answer: 60°C.
- A 20°C
- B 40°C
- C 60°C
- D 80°C
Correct answer: C. 60°C
Explanation: Initial excess temperature = body temperature minus surrounding temperature = 80°C - 20°C = 60°C, the driving temperature difference that determines the initial cooling rate.
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.