Fig. 8.1 shows a water manometer. When the water manometer is connected to a sealed container of gas and the tap is opened, the water levels change, as shown in Fig. 8.2.[Figure 8.1][Figure 8.2]

1. (a)Define pressure.[1]
2. (b)(i)Explain why the water levels are the same on both sides of the manometer in Fig. 8.1.[1]
3. (b)(ii)Explain why the water levels change when the gas tap is opened with the manometer connected as in Fig. 8.2.[1]
4. (b)(iii)Explain why the water levels stop changing at the levels shown in Fig. 8.2.[1]
5. (c)The water in the manometer has a density of 1000kg/m³. Atmospheric pressure is 1.00 × 10⁵ Pa and the gravitational field strength g is 10m/s². Calculate the pressure of the gas inside the sealed container. Give your answer to 3 significant figures.[4]
6. (d)The temperature of the gas inside the sealed container increases. Using ideas about molecules explain why the water levels change.[4]
7. (e)(i)This manometer is not suitable for measuring a gas pressure of 2.5 × 10⁵ Pa. Explain why.[2]
8. (e)(ii)State one change to this manometer that allows it to measure a gas pressure of 2.5 × 10⁵ Pa in a normal school laboratory.[1]

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