(a)[1]
Explain how Fig. 4.1 indicates that the melting temperature of the wax is 63^{\circ}C.
(b(i))[3]
The wax in the test-tube has a mass of 0.040 kg and its starting temperature at time t = 0 is 21^{\circ}C. The specific heat capacity of wax is 2100 J / (kg^{\circ}C). Using Fig. 4.1, determine the increase in the energy in the internal energy store of the wax between t = 0 and t = 220 s. Show your working.
(b(ii))[2]
Describe what happens to the motion of the molecules in solid wax as the internal energy of the wax increases.
(c)[2]
When the wax reaches its melting temperature, thermal energy keeps being transferred to the wax. Describe, in terms of the forces between particles, why energy is needed for the wax to melt.