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
deduce the nature (aldehyde or ketone) of an unknown carbonyl compound from the results of simple tests (Fehling’s and Tollens’ reagents; ease of oxidation)
recall the reactions (reagents and conditions) by which alkanes can be produced: (a) addition of hydrogen to an alkene in a hydrogenation reaction, \( H_2(g) \) and Pt/Ni catalyst and heat (b) cracking of a longer chain alkane, heat with \( Al_2O_3 \)
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
