A 150 g piece of solid wax at 40°C is placed on an 80°C metal plate. Determine the entropy changes of (i) the molten wax, (ii) the metal plate, and (iii) the universe, assuming that the temperature of the metal plate remains constant as the wax melts and subsequently reaches thermal equilibrium. Take the latent heat of fusion of wax to be 2.0 × 10⁵ J/kg, specific heat to be  2100 J/(kg.K), and its melting temperature to be 40°C.

• A. i) 1.4 × 10³ J/K, ii) - 1.8 × 10² J/K, iii) 16 J/K
• B. i) 1.4 × 10² J/K, ii) - 1.2 × 10³ J/K, iii) 18 J/K
• C. i) 1.3 × 10³ J/K, ii) - 1.8 × 10³ J/K, iii) 14 J/K
• D. i) 1.3 × 10² J/K, ii) - 1.2 × 10² J/K, iii) 14 J/K

Answer: (D)