Important Exam Practice Questions for IGCSE Chemistry (0620) Topic: Particulate Nature of Matter 1. The diagram shows an experiment to demonstrate diffusion. [1] Which statement explains why the ring of ammonium chloride appears as shown? A Ammonia solution only produces a gas which moves until it meets the hydrochloric acid. B Both solutions produce a gas, but ammonia moves quicker than hydrogen chloride because it is lighter. C Hydrochloric acid produces hydrogen chloride which stays at one end of the tube until the ammonia reaches it. D The two solutions run along the tube until they meet. 2. In which substance are the particles close together and slowly moving past each other? [1] A air B ice C steam D water 3. A gas jar of bromine vapour and a gas jar of air are set up as shown in diagram 1. The glass slide is removed. Diagram 2 shows the appearance of the gas jars after one hour. Which statement explains why the bromine and air mix t...