The table shows the specific heat capacities of different materials:
| Material | Specific heat capacity (J/kg∘C\text{J/kg}^\circ\text{C}J/kg∘C) |
|---|---|
| Lead | 130 |
| Silver | 233 |
| Copper | 385 |
| Iron | 450 |
| Steel | 490 |
| Granite | 790 |
A scientist heats an unknown substance from a solid to a liquid.
The graph shows how the temperature of the substance varies with time.
The scientist has 2.0 kg2.0\text{ kg}2.0 kg of the substance and records that it takes 405 kJ405\text{ kJ}405 kJ of energy to increase its temperature from the lowest to the highest temperature in the liquid state.
a.[5]
Use the graph to calculate the specific heat capacity of the substance. Suggest what material it could be from the table.
b.[2]
Suggest two reasons why the scientist cannot be certain that the substance has been identified correctly.