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
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
state and explain the variation in the oxidation number of the oxides (Na₂O, MgO, Al₂O₃, P₄O₁₀, SO₂ and SO₃ only) and chlorides (NaCl, MgCl₂, AlCl₃, SiCl₄, PCl₆ only) in terms of their outer shell (valence shell) electrons
write formulas of ionic compounds from ionic charges and oxidation numbers (shown by a Roman numeral), including: (a) the prediction of ionic charge from the position of an element in the Periodic Table (b) recall of the names and formulas for the following ions: \(NO_3^-\), \(CO_3^{2-}\), \(SO_4^{2-}\), \(OH^-\), \(NH_4^+\), \(Zn^{2+}\), \(Ag^+\), \(HCO_3^-\), \(PO_4^{3-}\)
