A sealed flask of air is placed in a freezer.
Which statement describes what happens to the air in the flask?
The particles slow down, so the pressure of the air decreases
The particles slow down, so the pressure of the air increases
The particles stop moving, so the pressure of the air becomes zero
The particles move closer together, so the pressure stays the same
50 exam-style questions on OCR GCSE Physics 1.3 Pressure, covering 1.3.1 Molecular motion, temperature and gas pressure, 1.3.2 Gas pressure at constant volume, 1.3.3 Compressing and expanding gases, 1.3.4 Gas volume and pressure at constant temperature, 1.3.5 Doing work on a gas, 1.3.6 The Earth's atmosphere and atmospheric pressure, 1.3.7 Atmospheric pressure and height, 1.3.8 Floating and sinking, 1.3.9 Pressure in liquids and upthrust, and 1.3.10 Pressure differences with depth. Each one has a worked solution and a mark scheme showing where the marks go.