State two other physical properties of materials, apart from the density of a liquid, that can be used for measuring temperature.
As shown in Fig. 2.1, the thermometer starts at $23.0\,^{\circ}\text{C}$. It is placed in an insulated beaker of water at $37.4\,^{\circ}\text{C}$. The thermometer bulb is put into the water, and the water is stirred until the thermometer reading stops changing. The mass of water in the beaker is $18.7\ \text{g}$. The mass of mercury in the thermometer is $6.94\ \text{g}$. The specific heat capacity of water is $4.18\ \text{J g}^{-1}\ \text{K}^{-1}$. The specific heat capacity of mercury is $0.140\ \text{J g}^{-1}\ \text{K}^{-1}$. The glass of the thermometer and the beaker containing the water can be treated as having negligible heat capacity. Calculate, to three significant figures, the final steady temperature shown by the thermometer in the water.
Suggest one change that could be made to the design of the thermometer that would enable it to give a more accurate measurement of temperature.
Explain why the thermometer in Fig. 2.1 does not provide a direct measurement of thermodynamic temperature.
Thermodynamic temperature $T$ may be determined by the behaviour of a type of substance for which $T$ is proportional to the product of pressure and volume. State the name of this type of substance.