Answer: radiation.
- A radiation
- B conduction
- C convection
- D diffusion
Correct answer: A. radiation
Explanation: Radiation travels as electromagnetic waves and needs no medium - as sunlight through space shows.
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.