Older MCQs might not have the typical A, B, C,
D
choices. They
have choices 1, 2, 3, and a combination of them is the answer. Below is the key that maps such
combinations to the answer.
A
1, 2 and 3 are correct
B
1 and 2 only are correct
C
2 and 3 only are correct
D
1 only is correct
perform calculations including use of the mole concept, involving: (a) reacting masses (from formulas and equations) including percentage yield calculations (b) volumes of gases (e.g. in the burning of hydrocarbons) (c) volumes and concentrations of solutions (d) limiting reagent and excess reagent (When performing calculations, candidates’ answers should reflect the number of significant figures given or asked for in the question. When rounding up or down, candidates should ensure that significant figures are neither lost unnecessarily nor used beyond what is justified (see also Mathematical requirements section)) (e) deduce stoichiometric relationships from calculations such as those in 2.4.1(a)–(d)
describe and interpret, in terms of changes in oxidation number, the reaction of chlorine with cold and with hot aqueous sodium hydroxide and recognise these as disproportionation reactions
describe, explain, and write equations for, the acid/base behaviour of the oxides Na₂O, MgO, Al₂O₃, P₄O₁₀, SO₂ and SO₃ and the hydroxides NaOH, Mg(OH)₂ and Al(OH)₃ including, where relevant, amphoteric behaviour in reactions with acids and bases (sodium hydroxide only)
