A test-tube contains solid wax. The melting point of the wax is 58°C. The test-tube is partially immersed in a beaker of boiling water and the wax melts. A thermometer is placed in the liquid wax. At time t = 0, the thermometer reads 90°C and the test-tube is immediately removed from the water. The test-tube then cools to room temperature of 23°C.

1. (a)On the axes of Fig. 5.1, sketch a graph to show how the temperature changes with time t. Mark on the temperature axis 90°C, 58°C and 23°C.[3]
2. (b)On the completed graph of Fig. 5.1, mark a point H, where half of the wax is solid and half is liquid.[1]
3. (c)The specific latent heat of fusion of the wax is 220J/g and the mass of the wax is 45 g. Calculate the thermal energy released by the wax as it solidifies.[2]

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