i) The catalyst used in the catalytic oxidation of ammonia to nitrogen oxide is platinum-rhodium gauze*.

Here are the solutions to the questions: f) i) The catalyst used in the catalytic oxidation of ammonia to nitrogen oxide is platinum-rhodium gauze*. ii) The balanced chemical equation for the reaction between ammonia and air (oxygen) is: 4NH_3(g) + 5O_2(g) Pt/Rh catalyst 4NO(g) + 6H_2O(g) iii) One environmental problem likely to be faced in an area where a nitric (V) acid manufacturing plant is located is acid rain or photochemical smog* due to the emission of nitrogen oxides. g) One source of nitrogen in the Haber process is air. 2) a) i) An element that can form an ion with a charge of -2 is R or S*. These elements are in Group 16 and gain two electrons to achieve a stable octet. ii) Q is an alkali metal (Group 1). The chloride of Q will have a giant ionic lattice structure*. iii) V is in Period 2, Group 17, and W is in Period 3, Group 17. Both are halogens. Reactivity of halogens decreases down the group. Therefore, V is more reactive than W*. This is because V has a smaller atomic radius, so its nucleus has a stronger attraction for an incoming electron, making it easier to gain an electron. iv) T is in Period 4, Group 1, and U is in Period 4, Group 2. Both are in the same period. Atomic radius decreases across a period from left to right. Therefore, T has a larger atomic radius than U*. This is because U has a greater nuclear charge than T, which pulls the electrons closer to the nucleus, resulting in a smaller atomic radius. That's 2 down. 3 left today — send the next one.