Basic concepts of organic chemistry: OCR A‑Level Chemistry A questions

Every OCR A-Level Chemistry A exam question on 4.1.1 Basic concepts of organic chemistry, 2016–2025, with its mark scheme and examiner’s report.

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Q1
June 2025 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q3
June 2025 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q16(a)
June 2025 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q21(a)
June 2025 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q2(a)(i)
June 2025 · Paper 3
1 mark4.1.1 Basic concepts of organic chemistry
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Q5(a)(i)
June 2025 · Paper 3
1 mark4.1.1 Basic concepts of organic chemistry
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Q14
June 2025 · AS Paper 1
1 mark4.1.1 Basic concepts of organic chemistry
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Q17
June 2025 · AS Paper 1
1 mark4.1.1 Basic concepts of organic chemistry
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Q4(c)
June 2025 · AS Paper 2
2 marks4.1.1 Basic concepts of organic chemistry
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Q4(d)(ii)
June 2025 · AS Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q16(a)
June 2024 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q16(b)
June 2024 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q16(c)
June 2024 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q2(c)(i)
June 2024 · Paper 3
1 mark4.1.1 Basic concepts of organic chemistry
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Q14
June 2024 · AS Paper 1
1 mark4.1.1 Basic concepts of organic chemistry
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Q15
June 2024 · AS Paper 1
1 mark4.1.1 Basic concepts of organic chemistry
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Q18
June 2024 · AS Paper 1
1 mark4.1.1 Basic concepts of organic chemistry
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Q3
June 2023 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q5
June 2023 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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Q7
June 2023 · Paper 2
1 mark4.1.1 Basic concepts of organic chemistry
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All 91 questions on Basic concepts of organic chemistry, as a list

June 2025, Paper 2, Q1 (1 mark): Which compound is alicyclic and unsaturated? A B C D Your answer [1]
June 2025, Paper 2, Q3 (1 mark): The skeletal structure of a medicinal drug is shown below. How many hydrogen atoms are in its molecular formula? H N Cl Cl A 14 B 15 C 17 D 19 Your answer [1]
June 2025, Paper 2, Q16(a) (1 mark): Compound A is a hydrocarbon: Compound A What is the systematic name of compound A? [1]
June 2025, Paper 2, Q21(a) (1 mark): What is a functional group? [1]
June 2025, Paper 3, Q2(a)(i) (1 mark): Draw the skeletal formula of 2,3‑dimethylhexan‑1‑ol. [1]
June 2025, Paper 3, Q5(a)(i) (1 mark): What is the systematic name of the alcohol C6H5CH2OH? [1]
June 2025, AS Paper 1, Q14 (1 mark): The skeletal formulae of four alcohols, W, X, Y, Z, are shown below. OH W OH X OH Y OH Z Which pair of alcohols are structural isomers of each other? A W and X
June 2025, AS Paper 1, Q17 (1 mark): How many structural isomers of C5H12O are secondary alcohols? A 1 B 2 C 3 D 4 Your answer [1]
June 2025, AS Paper 2, Q4(c) (2 marks): Besides pentane, there are two other structural isomers of C5H12. Draw the skeletal formulae of these two other structural isomers and state the systematic name
June 2025, AS Paper 2, Q4(d)(ii) (1 mark): The first step in the mechanism of the reaction is the homolytic fission of a Br–Br bond. Explain what is meant by homolytic fission. [1]
June 2024, Paper 2, Q16(a) (1 mark): Which hydrocarbons are unsaturated? [1]
June 2024, Paper 2, Q16(b) (1 mark): Which hydrocarbons are alicyclic? [1]
June 2024, Paper 2, Q16(c) (1 mark): Which hydrocarbons have the general formula CnH2n? [1]
June 2024, Paper 3, Q2(c)(i) (1 mark): What is the molecular formula of compound B? [1]
June 2024, AS Paper 1, Q14 (1 mark): What is the name of the compound below? Cl OH A 1‑chloro‑1,2‑dimethylpropan‑3‑ol B 2‑chloro‑3‑methylbutan‑4‑ol C 3‑chloro‑2‑methylbutan‑1‑ol D 3‑chloro‑2,3‑dime
June 2024, AS Paper 1, Q15 (1 mark): The structure of a hydrocarbon is shown below. Which terms describe this hydrocarbon? A Alicyclic and saturated B Aliphatic and alicyclic C Aliphatic and aromat
June 2024, AS Paper 1, Q18 (1 mark): Which functional groups are present in the compound below? O O OH A Alcohol and aldehyde. B Alcohol and ketone. C Carboxylic acid and aldehyde. D Carboxylic aci
June 2023, Paper 2, Q3 (1 mark): Propyne, CH3C≡CH, is a member of the alkynes homologous series with the C≡C functional group. What is the general formula of the alkynes? A CnH2n–4 B CnH2n–2 C
June 2023, Paper 2, Q5 (1 mark): Oxymetazoline, shown below, is used as a decongestant in the treatment of colds. HO N HN Oxymetazoline How many H atoms are in one molecule of oxymetazoline? A
June 2023, Paper 2, Q7 (1 mark): What is the systematic name for the compound below? A 3,5-dimethylocta-1,3,6-triene B 3,5-dimethylocta-2,5,7-triene C 4,6-dimethylocta-1,3,6-triene D 4,6-dimeth
June 2023, Paper 2, Q13 (1 mark): Which compound(s) is/are aliphatic? 1 2 3 A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
June 2023, Paper 3, Q2(c) (4 marks): The benzenediazonium ion, shown below, is stable at temperatures below 10 °C. + N N Benzenediazonium Above 10 °C, the benzenediazonium ion reacts with water to
June 2023, AS Paper 1, Q15 (1 mark): Which formula does not represent 3-methylbut-1-ene? A CH3CHCH3CHCH2 B CH2CHCH(CH3)2 C D Your answer [1]
June 2023, AS Paper 1, Q16 (1 mark): How many structural isomers have the molecular formula C4H9Cl ? A 2 B 3 C 4 D 5 Your answer [1]
June 2023, AS Paper 2, Q5(a)(i) (1 mark): What is the systematic name of alcohol A? [1]
June 2022, Paper 2, Q16(a)(i) (1 mark): What is the systematic name of hydrocarbon A? [1]
June 2022, Paper 2, Q16(b)(i) (1 mark): What is meant by the term structural isomers? [1]
June 2022, Paper 2, Q16(c)(ii) (1 mark): The mechanism for ozonolysis takes place in several steps. The curly arrows in the first step in the ozonolysis of methylbut-2-ene are shown below. In the box,
June 2022, Paper 3, Q6(c)(i) (2 marks): In aqueous solution, vitamin C donates a proton to water: – + H3O+ C6H8O6 + H2O C6H7O6 Add curly arrows to the diagram to suggest the mechanism for this process
June 2022, AS Paper 1, Q15 (1 mark): What is the number of hydrogen atoms in one molecule of the compound below? O OH A 8 B 10 C 12 D 14 Your answer [1]
June 2022, AS Paper 1, Q21(a)(i) (1 mark): What is the systematic name for (CH3)3CCH=CH2? [1]
November 2021, Paper 2, Q16(d)(i) (2 marks): Add curly arrows to the diagram below to complete the mechanism for this Diels-Alder reaction. [2]
November 2021, Paper 2, Q18(c)(i) (1 mark): What is the molecular formula of ibuprofen? [1]
November 2021, Paper 2, Q19(a)(i) (1 mark): What is the systematic name for prenal? [1]
November 2021, AS Paper 1, Q14 (1 mark): What do curly arrows always show in reaction mechanisms? A Movement of one electron. B Movement of a pair of electrons. C Movement of a lone pair of electrons.
November 2021, AS Paper 1, Q17 (1 mark): What is the systematic name of the compound below? OH A 3-methylhex-5-en-4-ol B 4-methylhex-1-en-3-ol C 2-ethylpent-4-en-3-ol D 4-ethylpent-1-en-3-ol Your answe
November 2021, AS Paper 1, Q18 (1 mark): The ‘dienes’ are a homologous series of non-cyclic compounds with two double bonds. The simplest diene is shown below. What is the general formula of the dienes
November 2021, AS Paper 1, Q21(d)(i) (1 mark): The systematic name for halothane is 2-bromo-2-chloro-1,1,1-trifluoroethane. Draw the structure of a halothane molecule. [1]
November 2021, AS Paper 1, Q24(b)(i) (1 mark): Explain the term structural isomer. [1]
November 2021, AS Paper 2, Q2(a) (1 mark): What is meant by a radical? [1]
November 2021, AS Paper 2, Q2(b) (1 mark): Name the type of bond breaking that occurs in a radical substitution reaction. [1]
November 2021, AS Paper 2, Q7(c)(i) (1 mark): Compound A is a secondary alcohol. What is the systematic name of compound A? [1]
November 2020, Paper 2, Q10 (1 mark): What is the number of alicyclic structural isomers of C5H10? A 3 B 4 C 5 D 6 Your answer [1]
November 2020, Paper 2, Q12 (1 mark): What is the molecular formula of the steroid molecule below? OH HO A C18H24O2 B C18H26O2 C C18H28O2 D C18H30O2 Your answer [1]
November 2020, Paper 2, Q16(a) (1 mark): Hydrocarbon A can be reacted with bromine in the presence of ultraviolet radiation to prepare (CH3)3CCHBrCH3. What is the systematic name for (CH3)3CCHBrCH3? [1
November 2020, Paper 2, Q19(a)(i) (2 marks): Explain the term homologous series. [2]
November 2020, Paper 2, Q19(a)(ii) (1 mark): Predict the molecular formula for the member of this homologous series containing 24 carbon atoms. [1]
November 2020, Paper 2, Q19(c)(ii) (2 marks): Explain why the mechanism in (c)(i) involves heterolytic fission. [2]
November 2020, Paper 3, Q6(c) (4 marks): Carboxylic acids and sulfonic acids both form esters. Sulfonic acid esters can be hydrolysed by aqueous alkali. The equation shows the alkaline hydrolysis of a
November 2020, AS Paper 1, Q14 (1 mark): Which statement is correct for the two structures below? A They have the same empirical formula. B They have different relative molecular masses. C They are str
November 2020, AS Paper 1, Q19 (1 mark): Which row describes a nucleophile? A electron pair donor attracted to high electron density B electron pair donor attracted to low electron density C electron p
November 2020, AS Paper 1, Q25(c)(i) (2 marks): Explain what is meant by the term: homologous series. [2]
November 2020, AS Paper 1, Q25(c)(ii) (1 mark): Suggest the general formula of the alkynes. [1]
November 2020, AS Paper 1, Q25(c)(iv) (2 marks): But-1-yne is a structural isomer of C4H6. Draw the structures of 2 other structural isomers of C4H6. [2]
November 2020, AS Paper 1, Q25(c)(v) (1 mark): Draw the structure of 2,5-dimethylhept-3-yne. [1]
November 2020, AS Paper 2, Q5(c) (1 mark): What is the systematic name of alcohol B? [1]
June 2019, Paper 2, Q3 (1 mark): What is the name of the compound below? H CH3 C C H3C CH2 CH2 CH2 CH3 A 3-Propylpent-2-ene B 3-Propylpent-3-ene C 3-Ethylhex-2-ene D 4-Ethylhex-4-ene Your answe
June 2019, Paper 2, Q16(b)(ii) (1 mark): What is the molecular formula of geraniol? [1]
June 2019, Paper 2, Q16(b)(iii) (1 mark): Explain why geraniol and citronellal are structural isomers of each other. [1]
June 2019, Paper 2, Q20(a)(i) (1 mark): What does a curly arrow show in a reaction mechanism? [1]
June 2019, Paper 2, Q20(a)(ii) (2 marks): Draw structures to show the products in the reaction mechanism below. H H + O [2]
June 2019, Paper 2, Q20(a)(iii) (2 marks): Use the mechanism in (ii) to explain what is meant by heterolytic fission. [2]
June 2019, Paper 2, Q20(b)(i) (4 marks): Complete the mechanism by adding curly arrows and any missing species. – O O H3C C H3C C Cl Cl OH – OH O H3C C + ………… OH [4]
June 2019, AS Paper 1, Q15 (1 mark): Which compound is unsaturated, alicyclic and contains an alkyl group? A B C D Your answer [1]
June 2019, AS Paper 1, Q25(a)(ii) (1 mark): Write the systematic name for alcohol C. [1]
June 2019, AS Paper 2, Q3(c)(i) (1 mark): Draw the structure of 2-iodo-2-methylbutane. [1]
June 2018, Paper 2, Q4 (1 mark): Which structure represents an alicyclic compound? A B C D Your answer [1]
June 2018, Paper 2, Q16(a)(i) (1 mark): What is the systematic name of alcohol A? [1]
June 2018, Paper 2, Q16(a)(ii) (1 mark): What is the structural formula of alcohol A? [1]
June 2018, Paper 3, Q6(a)(i) (1 mark): Give the systematic name for compound A. [1]
June 2018, Paper 3, Q6(a)(ii) (1 mark): What type of reaction has taken place? [1]
June 2018, AS Paper 1, Q17 (1 mark): The structure of naphthalene is shown below. What is the molecular formula of naphthalene? A C10H8 B C10H10 C C12H10 D C12H12 Your answer [1]
June 2018, AS Paper 1, Q24(a) (5 marks): Compounds A, B and C are saturated hydrocarbons. The structures and boiling points of A, B and C are shown below. Isomer Boiling point / °C A 36 B 28 C 9 • Use
June 2018, AS Paper 1, Q25(a)(ii) (1 mark): What is the systematic name of alcohol E? [1]
June 2018, AS Paper 2, Q1(d)(ii) (1 mark): A is an organic acid, containing C, H and O only. One molecule of A contains two COOH groups. Suggest the structure of A. [1]
June 2018, AS Paper 2, Q6(b)(i) (1 mark): Give the systematic name of compound D. [1]
June 2017, Paper 2, Q2 (1 mark): How can the molecule below be described? OH A Aromatic and alicyclic B Aliphatic and unsaturated C Aromatic and unsaturated D Alicyclic and saturated Your answe
June 2017, Paper 2, Q9 (1 mark): What is the molecular formula of the compound below? A C7H10 B C7H12 C C7H14 D C7H16 Your answer [1]
June 2017, Paper 2, Q15 (1 mark): Which compound(s) is a/are structural isomer(s) of C6H12O2? 1 hexanoic acid 2 ethyl butanoate 3 propyl propanoate A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D O
June 2017, Paper 2, Q16(b)(i) (1 mark): Name compound C. [1]
June 2017, Paper 2, Q19(c)(ii) (1 mark): What is the name of compound K? [1]
June 2017, Paper 3, Q3(c)(i) (1 mark): Suggest the structure for CH3COOOH. The COOOH functional group must be clearly displayed. [1]
June 2017, Paper 3, Q5(a)(iii) (1 mark): When beer is exposed to light, 3-methylbut-2-ene-1-thiol is formed, which gives an unpleasant smell and flavour to the beer. Draw the skeletal formula for 3-met
June 2017, AS Paper 1, Q15 (1 mark): The skeletal formula of an organic compound is shown below. O OH What is the molecular formula of the organic compound? A C6H10O2 B C6H11O2 C C6H12O2 D C6H13O2
June 2017, AS Paper 1, Q16 (1 mark): How many structural isomers have the molecular formula C5H12? A 2 B 3 C 4 D 5 Your answer [1]
June 2017, AS Paper 2, Q4(b)(i) (1 mark): Give the systematic name of alcohol C. [1]
June 2017, AS Paper 2, Q5(a) (1 mark): Suggest the general formula for a carboxylic acid. [1]
June 2017, AS Paper 2, Q5(d)(iii) (1 mark): The first step in the reaction mechanism involves homolytic fission of a chlorine molecule to form two chlorine radicals. Why is this step an example of homolyt
June 2016, AS Paper 1, Q13 (1 mark): The skeletal formulae of four alcohols, E, F, G and H, are shown below. OH OH E F OH HO G H Which pair of alcohols are structural isomers of each other? A E and
June 2016, AS Paper 1, Q14 (1 mark): What is the name of the following compound? Cl Cl H3C C C CH3 H CH3 A 1,2-dichloro-1,2-dimethylpropane B 2,3-dichloro-2,3-dimethylpropane C 2,3-dichloro-2-methy
June 2016, AS Paper 1, Q26(a)(i) (1 mark): Compound B is a member of a homologous series. Name the homologous series and state its general formula. Homologous series General formula [1]

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