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: $$4\text{NH}_3(g) + 5\text{O}_2(g) \xrightarrow{\text{Pt/Rh catalyst}} 4\text{NO}(g) + 6\text{H}_2\text{O}(g)$$
• 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.