1. Hydrogen can be prepared by reacting zinc with dilute hydrochloric acid. a) Write an equation for the reaction. b) Name an appropriate drying agent for hydrogen gas. c) Explain why copper metal cannot be used to prepare hydrogen gas. d) Hydrogen burns in oxygen to form an oxide. (i) Write an equation for the reaction. (ii) State two precautions that must be taken before the combustion begins and at the end of the combustion. e) Give two uses of hydrogen gas. f) When zinc is heated to redness in a current of steam, hydrogen gas is obtained. Write an equation for the reaction. g) Element Q reacts with dilute acids but not with cold water. Element R does not react with dilute acids. Elements S displaces element P from its oxide. P reacts with cold water. Arrange the four elements in order of their reactivity, starting with the most reactive. h) Explain how hydrogen is used in the manufacture of margarine. 2. (a) Hydrogen can reduce coppers Oxide but not aluminium oxide. Explain (b) When water reacts with potassium metal the hydrogen produced ignites Explosively on the surface of water. (i) What causes this ignition? (ii) Write an equation to show how this ignition occurs 3. Element E has an atomic number of 5. In a sample of E there are two isotopes. One isotope has a mass number of 10 and the other isotope has a mass number of 11. a. Explain, in terms of subatomic particles, what is meant by the term isotopes. b. Element X has an atomic number of 18. c. State the electronic configuration of an atom of element X. 4. The electronic structures of five atoms, A, B, C, D and E, are shown. D Answer the following questions about these structures. Each structure may be used once, more than once or not at all. State which structure, A, B, C, D or E, represents: a. An atom of a metallic element. b. An atom with a proton number of 13. C. An atom of phosphorus. d. An atom with only two shells of electrons. e. An atom which forms a stable ion with a single negative charge.
