Organic chemistry (general) — AS & A Level Chemistry (9701) questions by topic
Empirical formulae and multi-step syntheses connect the questions here: deducing hexamine's empirical formula from its cage structure, stating reagents for converting benzene to methylbenzene then benzoic acid, and describing carbon-13 NMR spectra by chemical-shift peak count.
Deduce, identify, calculate, state and suggest lead 22 questions from 2023 to 2025 papers, worth 1 to 16 marks, where a wrongly charged manganate ion or a skipped NMR detail can lose an otherwise earned mark. Submitting reagent and spectrum-description answers for instant marking flags a manganate(VII) ion mistakenly written as MnO4^2- before that formula error resurfaces in a later redox question.
What examiners look for
- A recurring criticism is writing the manganate(VII) ion as MnO4^2-, MNO4-, mNO4- or mno4- rather than MnO4-.
- Examiners note descriptions of carbon-13 NMR spectra often ignored the number of peaks in each chemical-shift range, even when told each compound has five peaks.
- Reports flag C6H5CO2Cl as a commonly seen wrong answer where a different structure was correct.
- Strong answers deduced the empirical formula C3H7O correctly from the molecular formula C6H14O2, and identified LiAlH4 as a suitable reducing agent.
- Candidates who correctly stated that the keto-acid reacts with all three given reagents scored well.
May–June 2025, Paper 11
P is a compound that burns in an excess of oxygen to give carbon dioxide and water only. 2.20 g of P contains 1.20 g of carbon and 0.20 g of hydrogen. When P is added to a…
Answer this question and get it marked →Complete combustion of compound T produces carbon dioxide and water only. Compound T produces steamy fumes with PCl5. Compound T does not give any visible product with…
Answer this question and get it marked →May–June 2025, Paper 12
The skeletal formulae of arginine and lysine are shown. Which row is correct? A arginine, empirical formula C3H7N2O, Mr 174 B arginine, empirical formula C3H8N2O, Mr 176 C lysine,…
Answer this question and get it marked →May–June 2025, Paper 13
The structure of a molecule found in food is shown (a glucose-like monosaccharide ring structure with CH2OH group). Four statements about the molecule are listed. 1 This molecule…
Answer this question and get it marked →An organic compound, T, contains only one functional group. Compound T has the empirical formula C2H4O. Some functional groups are listed. 1 alcohol 2 aldehyde 3 ester 4 ketone…
Answer this question and get it marked →May–June 2025, Paper 14
What is the empirical formula of butanoic acid? A C2H4O B C3H6O C C4H8O D C5H10O
Answer this question and get it marked →Quinone is an unsaturated molecule (para-quinone structure: two C=O groups on a cyclohexadiene ring). Which statement about quinone is correct? A Quinone is non-planar and has an…
Answer this question and get it marked →May–June 2025, Paper 22
C3H6 reacts with HBr(g) in an addition reaction. (i) Define addition reaction. (ii) Complete Fig. 3.1 to show the mechanism for the addition reaction between C3H6 and HBr to…
Answer this question and get it marked →May–June 2025, Paper 23
Different hydrocarbon mixtures produced from fractional distillation of crude oil have different uses. (i) State the compound that is heated with long-chain hydrocarbons to…
Answer this question and get it marked →HOCl reacts with CH2=CH2 to produce HOCH2CH2Cl in an electrophilic addition reaction. (i) Define addition reaction. (ii) Describe how Cl2 is used to produce HOCl. (iii) State one…
Answer this question and get it marked →May–June 2025, Paper 24
P, Q and R are three different hydrocarbon molecules. Hydrocarbon P contains 85.7% by mass of carbon. (i) Define empirical formula. (ii) Calculate the empirical formula of P. Show…
Answer this question and get it marked →May–June 2024, Paper 11
The diagram shows the skeletal formula of citric acid: a central carbon bearing an OH group and a CH2COOH group on each side and a COOH group directly attached. What is the…
Answer this question and get it marked →May–June 2024, Paper 12
In the general formula of which class of compound is the ratio of hydrogen atoms to carbon atoms the highest? A alcohols B aldehydes C carboxylic acids D halogenoalkanes
Answer this question and get it marked →May–June 2023, Paper 11
An organic molecule W contains 3 carbon atoms. It requires 4.5 molecules of oxygen for complete combustion. What could W be? A propane B propanoic acid C propanone D propan-1-ol
Answer this question and get it marked →May–June 2023, Paper 12
Which compound has the molecular formula C6H10O? Four skeletal structures are shown: A is a cyclopentane ring with a C=O group (cyclopentanone), B is 3,3-dimethylbutan-2-one type…
Answer this question and get it marked →May–June 2023, Paper 13
Methylbut-2-ene reacts with HBr at room temperature to produce compound X as a major product. Compound X reacts with KCN in ethanol to produce compound Y. Compound Y is hydrolysed…
Answer this question and get it marked →May–June 2023, Paper 23
Y is formed from X in a single-step reaction, as shown in Fig. 5.1. X is hexane-2,5-dione type keto-acid (a straight-chain molecule containing a ketone C=O group and a carboxylic…
Answer this question and get it marked →October–November 2023, Paper 11
Hexamine is a crystalline solid used as a fuel in portable stoves; the diagram shows its skeletal structure (a cage molecule containing six CH2 groups and four nitrogen atoms).…
Answer this question and get it marked →How many sigma and pi bonds are in the molecule HCCCH2CH2CHC(CH3)2? A: 17 sigma 3 pi. B: 17 sigma 5 pi. C: 18 sigma 4 pi. D: 19 sigma 3 pi.
Answer this question and get it marked →October–November 2023, Paper 12
Artemisinin is a powerful anti-malarial drug; its skeletal structure is shown. How many chiral centres are there in each molecule of artemisinin? A: 4. B: 6. C: 7. D: 8.
Answer this question and get it marked →Propanoic acid can be used to make propene by a two-stage synthesis. Which row shows suitable reagents for this synthesis? A: first stage LiAlH4, second stage conc. H2SO4. B:…
Answer this question and get it marked →October–November 2023, Paper 42
Benzene can be used to make benzoic acid in a two-step process (Fig. 7.1): benzene → (step 1) methylbenzene → (step 2) benzoic acid. Give the reagents and conditions for step 1…
Answer this question and get it marked →Other AS & A Level Chemistry topics
- Practical skills (106)
- Hydrocarbons (65)
- Chemical bonding (63)
- The Periodic Table: chemical periodicity (59)
- Chemical energetics (53)
- Equilibria (53)
- Introduction to organic chemistry (53)
- Reaction kinetics (52)
- Carboxylic acids and derivatives (52)
- Group 2 (51)
- Carbonyl compounds (45)
- Atomic structure (44)