A mass of 0.45 kg0.45\text{ kg}0.45 kg of a certain substance is in the solid state in a well-insulated container. The substance is heated at a constant rate of 1.8×104 J/minute1.8 \times 10^4\text{ J/minute}1.8×104 J/minute.
At 3.0 minutes3.0\text{ minutes}3.0 minutes after starting the heating, the substance is all at the same temperature, and it starts to melt.
At 13.5 minutes13.5\text{ minutes}13.5 minutes after starting the heating, the substance finishes melting and the temperature starts to rise again.
Calculate the specific latent heat of fusion of the substance.
After 13.5 minutes13.5\text{ minutes}13.5 minutes of heating, when the temperature starts rising again, in which state is the substance?
Describe what happens to the molecules as thermal energy is supplied to them in this state.
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.