State two further physical properties of materials, apart from the density of a liquid, that may be used to measure temperature.
The thermometer starts at $23.0\,^{\circ}\text{C}$, as shown in Fig. 2.1. It is then placed in an insulated beaker of water at $37.4\,^{\circ}\text{C}$. The bulb is dipped into the water, and the water is stirred until the thermometer reading settles. The beaker contains $18.7\,\text{g}$ of water, and the mercury in the thermometer has a mass of $6.94\,\text{g}$. The specific heat capacity of water is $4.18\,\text{J g}^{-1}\text{K}^{-1}$, while that of mercury is $0.140\,\text{J g}^{-1}\text{K}^{-1}$. The glass of the thermometer and the beaker may be taken to have negligible heat capacity. Calculate, to three significant figures, the final steady temperature shown by the thermometer in the water.
Suggest one change to the design of the thermometer that would allow it to measure temperature more accurately.
Explain why the thermometer in Fig. 2.1 does not measure thermodynamic temperature directly.
Thermodynamic temperature $T$ can be found from the behaviour of a substance type for which $T$ is proportional to the product of pressure and volume. State the name of this type of substance.