a) i) State Boyle's Law and Charles' Law. (4 marks) ii) Sketch a clearly labelled graph to show how the pressure of a fixed mass of gas at constant temperature varies with the volume of the gas. (2 marks) b) A weather balloon is filled with 2.0 moles of helium gas at sea level where the temperature is 17°C and the pressure is 1.01 × 10⁵ Pa. Calculate: i) the volume of the balloon at sea level. (3 marks) ii) the new volume of the balloon when it rises to an altitude where the pressure is 5.0 × 10⁴ Pa and the temperature is −23°C. (3 marks) [Molar gas constant R = 8.314 J mol⁻¹ K⁻¹] c) i) Define the term 'vapour pressure'. (1 mark) ii) Explain why the boiling point of water decreases at high altitudes. (2 marks) d) State one industrial application of the knowledge of gas laws. (1 mark)