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: (a) the reaction with oxygen (combustion) (b) substitution to form halogenoalkanes, e.g. by reaction with HX(g); or with KCl and concentrated \( H_2SO_4 \) or concentrated \( H_3PO_4 \); or with PCl\(_3\) and heat; or with PCl\(_5\); or with SOCI\(_2\) (c) the reaction with Na(s) (d) oxidation with acidified \( K_2Cr_2O_7 \) or acidified KMnO\(_4\) to: (i) carbonyl compounds by distillation (ii) carboxylic acids by refluxing (primary alcohols give aldehydes which can be further oxidised to carboxylic acids, secondary alcohols give ketones, tertiary alcohols cannot be oxidised) (e) dehydration to an alkene, by using a heated catalyst, e.g. \( Al_2O_3 \) or a concentrated acid (f) formation of esters by reaction with carboxylic acids and concentrated \( H_2SO_4 \) as catalyst as exemplified by ethanol
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)
