An apparatus is used to verify a gas law. The glass jar contains a fixed volume of air. Measurements can be taken using the thermometer and the pressure gauge. The apparatus is cooled in a freezer and then placed in a water bath so that the temperature of the gas increases slowly. The pressure and temperature of the gas are recorded.

The graph shows the data recorded. Identify the fundamental SI unit for the gradient of the pressure-temperature graph.

The experiment is repeated using a different gas in the glass jar. The pressure for both experiments is low and both gases can be considered to be ideal. Using the axes provided in , draw the expected graph for this second experiment.

Explain the shape and intercept of the graph you drew in (i).