Answer: (7/2)R.
- A (5/2)R
- B (7/2)R
- C (3/2)R
- D (9/2)R
Correct answer: B. (7/2)R
Explanation: Using Mayers relation Cp = Cv + R = (5/2)R + R = (7/2)R.
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.