The question was attempted by most candidates and the performance was poor.

In part (a), candidates were unable to outline how a mixture of ammonium chloride, potassium chloride and lead (II) chloride could be separated in the laboratory. The expected answers from candidates were as follows:

- Pour the mixture into an evaporating dish and cover with a glass funnel.
- Heat the mixture
- Ammonium chloride sublimes and collects in the funnel
- Add distilled water to the mixture
- Potassium chloride dissolves
- Filter and collect the lead (II) chloride as residue
- Evaporate the filtrate to dryness to obtain potassium chloride.

In part (b), candidates correctly named calcium chloride/calcium oxide/Silica gel as solid drying agent in (i) and concentrated tetraoxosulphate (VI) acid as liquid drying agent in (II).

In part (c), candidates correctly mention one laboratory apparatus used in(i)-(v) as follows:
(i)       Volumentric/standard flask
(ii)      Liebig condenser
(iii) desiccators
(iv) kipps apparatus
(v)      pH meter.

In part (d) (i), candidates could not describe a chemical test to distinguish between pure water and sodium tetraoxosulphate (VI) solution. The required description from candidates was as follows:

- To a sample of each liquid, add BaCl2(aq)
- The sample that forms white precipitate is sodium tetraoxosulphate(V1)
- No precipitate shows the presence of pure water.

In(d) (ii), only few candidates stated NaOH(aq)/NH3(aq) as the reagent suitable to distinguish the two white substances.