Answer: 3.
- A 3
- B 9
- C 27
- D 81
Correct answer: A. 3
Explanation: E ∝ T⁴, so if E increases by 81 = 3⁴, then T increased by a factor of 3.
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.