In an experiment, a thermometer is placed in a test-tube of a hot liquid substance. As the liquid cools, its temperature is recorded every minute. The table below shows the results:
Time / minutes0.01.02.03.04.05.06.07.08.09.010.0Temperature / ∘C9281726464645751464239\begin{array}{|l|c|c|c|c|c|c|c|c|c|c|c|} \hline \text{Time / minutes} & 0.0 & 1.0 & 2.0 & 3.0 & 4.0 & 5.0 & 6.0 & 7.0 & 8.0 & 9.0 & 10.0 \\ \hline \text{Temperature / } ^\circ\text{C} & 92 & 81 & 72 & 64 & 64 & 64 & 57 & 51 & 46 & 42 & 39 \\ \hline \end{array}Time / minutesTemperature / ∘C0.0921.0812.0723.0644.0645.0646.0577.0518.0469.04210.039What is the melting point of the substance?
0∘C0^\circ\text{C}0∘C
39∘C39^\circ\text{C}39∘C
64∘C64^\circ\text{C}64∘C
92∘C92^\circ\text{C}92∘C
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.