Physics · Oct / Nov 2018 · Paper 12 · Question 19

A 100 g piece of solid lead at room temperature is heated. After 22 s, it has all become liquid. The graph shows how its temperature varies with time. [graph: temperature / °C against time / s, showing heating from room temperature to a plateau at about 327 °C between 15 s and 22 s, then rising again] The power of the heater is 320 W. Which expression gives the specific latent heat, in J / kg, of the lead?

1. A\frac{7.0 \times 320}{0.10 \times 300}
2. B\frac{22 \times 320}{0.10 \times 300}
3. C\frac{7.0 \times 320}{0.10}
4. D\frac{22 \times 320}{0.10}

As printed in the paper