Answer: Radiation.
- A Conduction
- B Convection
- C Radiation
- D Diffusion
Correct answer: C. Radiation
Explanation: Radiation is heat transfer through electromagnetic waves and does not require any medium, hence it can occur through vacuum (e.g., sunlight reaching Earth).
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.