Practise 28 real questions on Hydroxy compounds from 2021 to 2026. See the answer and explanation as soon as you answer.
Hydroxy compounds is one of the 18 main topics in our A Level Chemistry (Cambridge (CAIE) 9701) question bank, and about 4% of its real questions come from it. Tayyari Karo has 28 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2, Paper 4; 26 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 16 hard, 11 medium, 1 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
A sample of 2.76 g of ethanol was mixed with excess aqueous acidified potassium dichromate(VI) and heated under reflux for one hour. The organic product was collected by distillation. The yield was 75.0%. Which mass of product was collected?
Answer: D. 2.70 g
Ethanol 2.76/46 = 0.0600 mol; reflux gives ethanoic acid (Mr 60): 0.0600 x 60 x 0.75 = 2.70 g.
A molecule of geraniol (a chain with two C=C double bonds, two methyl branches, and a terminal CH2OH group) is reacted with an excess of cold, dilute, acidified MnO4⁻. What is formed?
Answer: A. A triol formed by syn dihydroxylation of both C=C double bonds, leaving the original CH2OH intact
Cold, dilute, acidified manganate(VII) adds two −OH groups across each C=C bond (syn dihydroxylation) without breaking any C–C bonds, converting both alkene units to diols and leaving the existing CH2OH group unaffected — giving a triol.
Structural isomerism and stereoisomerism should be considered. If a molecule contains two non-identical chiral carbon atoms, four optical isomers exist. How many isomers are there with molecular formula C7H14O, a five-membered ring, and a tertiary alcohol group?
Answer: C. 9
Considering all positions for a tertiary -OH substituent (with methyl/ethyl side-chain combinations) on a cyclopentane ring of formula C7H14O, including the extra optical isomers from non-identical chiral centres, gives a total of 9 isomers.
How many structurally isomeric secondary alcohols are there with the molecular formula C5H12O?
Answer: C. 3
The secondary alcohols of C5H12O are pentan-2-ol, pentan-3-ol, and 3-methylbutan-2-ol — 3 structural isomers.
For which pair is the boiling point of the first compound higher than the boiling point of the second compound? A CH3CH2OH and CH3CH2SH; B CH3CO2CH3 and CH3CH2CO2H; C CH3OCH3 and CH3CH2OH; D CH3CH2CHO and CH3CH2CO2H
Answer: A. CH3CH2OH and CH3CH2SH
Ethanol (bp 78 °C) hydrogen bonds much more strongly than ethanethiol (bp 35 °C, S-H hydrogen bonds are weak), so ethanol has the higher boiling point.
How many chiral carbon atoms are there in one molecule of 2,2,4,5-tetramethylhexan-3-ol?
Answer: B. 2
Numbering the hexan-3-ol chain with methyl substituents at 2,2,4,5, carbons C3 (bearing OH) and C4 (bearing a methyl) each have four different substituents, giving 2 chiral centres.
| Session | Paper 1 | Paper 2 | Paper 4 |
|---|---|---|---|
| May/June 2026 | 1 | 1 | – |
| May/June 2025 | 2 | – | – |
| October/November 2025 | 2 | – | – |
| May/June 2024 | 2 | – | 1 |
| October/November 2024 | 2 | – | – |
| May/June 2023 | 4 | – | – |
| October/November 2023 | 3 | – | – |
| May/June 2022 | 3 | – | – |
| October/November 2022 | 3 | – | – |
| May/June 2021 | 1 | – | – |
| October/November 2021 | 3 | – | – |
28 real A Level Chemistry (9701) questions on Hydroxy compounds from 2021 to 2026, from Paper 1, Paper 2, Paper 4. Each one shows the year, session and paper it came from.
Yes. Every question shows the correct answer and a short explanation the moment you answer.
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