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Alkanes

Past-paper questions pack

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Questions are numbered; the mark schemes (the answer key) follow on separate pages so the question pages can be handed out alone. www.chemistryaleveltutor.com

OCR AS and A-level Chemistry past-paper questions since 2016 · 69 parts · mark schemes follow the questions · www.chemistryaleveltutor.com · Questions and mark schemes © OCR

1. June 2025 · AS Paper 1 · Q24(b) · 1 marks ·
(b) Pentene, C5H10, can undergo complete combustion to produce the same products as the combustion of an alkane. Write the equation for the complete combustion of C5H10. .................................................................................................................................................... [1]
2. June 2025 · AS Paper 2 · Q4(a) · 4 marks ·
4 The alkanes belong to a homologous series of hydrocarbons. Table 4.1 shows information about some straight chain alkanes. Table 4.1 Alkane Molecular Boiling point Enthalpy change of formula / °C combustion / kJ mol–1 Propane C3H8 –42 –2219 Butane C4H10 0 To estimate in part (b)(iv) Pentane C5H12 36 –3509 Hexane C6H14 69 –4163 (a) State and explain the trend in boiling points of the straight chain alkanes in Table 4.1. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [4]
3. June 2025 · AS Paper 2 · Q4(b)(i) · 1 marks ·
(b) When alkanes undergo complete combustion carbon dioxide and water are produced. (i) Write the balanced equation for the complete combustion of one mole of pentane. ..................................................................................................................................................... [1]
4. June 2025 · AS Paper 2 · Q4(d)(i) · 1 marks ·
(d) In the presence of ultraviolet radiation, propane reacts with bromine to form a mixture of products. Two of these products are structural isomers of C3H7Br. (i) Write an equation, using molecular formulae, for the formation of C3H7Br from propane. ..................................................................................................................................................... [1]
5. June 2025 · AS Paper 2 · Q4(d)(iii) · 2 marks ·
(iii) Complete the equations for the propagation steps in the mechanism. Use molecular formulae for organic species and dots (•) for unpaired electrons on radicals. C3H8 + Br• ............................ + ............................ ............................ + ............................ C3H7Br + ............................ [2]
6. June 2025 · AS Paper 2 · Q4(d)(iv) · 1 marks ·
(iv) Explain why two structural isomers of C3H7Br are formed. .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [1]
7. June 2025 · AS Paper 2 · Q5(a)(ii) · 2 marks ·
(ii) Name the shape of the chloromethane molecule and predict the value of the H–C–Cl bond angle. Name of shape .................................................................................................................................. Bond angle ........................................................................................................................................ [2]
8. June 2025 · Paper 2 · Q16(b) · 3 marks ·
(b) The table below shows incomplete information about two hydrocarbons. Complete the table. Skeletal formula Molecular formula Number of σ bonds Number of π bonds [3]
9. June 2025 · Paper 2 · Q16(d) · 1 marks ·
(d) Hexane, C6H14, is used as a fuel. 1.0 mol of hexane is mixed with 6.0 mol of oxygen and combusted. Construct an equation for the incomplete combustion of 1.0 mol of hexane with 6.0 mol of oxygen. ..................................................................................................................................................... [1]
10. June 2024 · AS Paper 1 · Q16 · 1 marks ·
16 Which property explains the low reactivity of alkanes? A Low C–C bond enthalpy. B Low bond enthalpy of π‑bonds. C Low polarity of σ‑bonds. D Low reactivity of carbon and hydrogen. Your answer [1]
11. June 2024 · AS Paper 1 · Q24(a) · 4 marks ·
24 This question is about hydrocarbons. (a) The skeletal formulae and boiling points of three isomers of C6H14 are shown in the table below. Molecular Boiling point / Isomer Skeletal formula formula °C A C6H14 69 B C6H14 63 C C6H14 58 State and explain the trend in the boiling points shown in the table. Refer to the isomers A, B and C in your answer. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [4]
12. June 2024 · AS Paper 1 · Q24(b) · 5 marks ·
(b) The hydrocarbon C2H6 reacts with bromine, Br2, to form C2H5Br under suitable conditions. Complete the table below to show the mechanism for the three stages of the reaction of C2H6 with Br2 to form C2H5Br. The equation for one of the possible reactions for termination has been completed. In your equations, use molecular formulae and ‘dots’ (•) with any radicals. Initiation Conditions ......................................................................................................... Equation ................................................... ................................................... Propagation 1 ......................................................... ......................................................... 2 ......................................................... ......................................................... Termination 1 Br• + Br• Br2 2 ......................................................... ......................................................... 3 ......................................................... ......................................................... [5]
13. June 2024 · AS Paper 1 · Q24(c) · 5 marks ·
(c) Propene, C3H6, has different bond angles and shapes around the carbon atoms. The displayed formula of a propene molecule is shown below. H H 1 H C C C H H 2 H Predict the bond angles and the names of the shapes around the C atoms 1 and 2 above, and explain why the bond angles and shapes are different. Carbon atom Bond angle Name of shape 1 2 Explanation: ..................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [5]
14. June 2024 · Paper 2 · Q4 · 1 marks ·
4 The structure of but-1-ene is shown below. x y Which row has the correct shape around carbon atoms labelled x and y? x y A Tetrahedral Pyramidal B Trigonal planar Tetrahedral C Trigonal planar Pyramidal D Pyramidal Tetrahedral Your answer [1]
15. June 2024 · Paper 2 · Q18(a)(i) · 3 marks ·
18 This question is about haloalkanes. (a) Haloalkanes can be synthesised by reacting alkanes with halogens in the presence of ultraviolet radiation. An alkane reacts with bromine to form 2-bromo-2-methylpropane. (i) Write the equation for this reaction, showing the structures of the organic compounds. Name the reaction mechanism and the type of bond fission that occurs. Equation Name of reaction mechanism .......................................................................................................... Type of bond fission ......................................................................................................................... [3]
16. June 2024 · Paper 2 · Q18(a)(ii) · 2 marks ·
(ii) Describe two limitations of the synthesis of 2-bromo-2-methylpropane from an alkane and bromine. 1 ....................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... 2 ....................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... [2]
17. June 2023 · AS Paper 1 · Q23(a)(i) · 2 marks · AO2
23 This question is about enthalpy changes. (a) In a petrol engine, alkanes undergo combustion. (i) Heptane is one of the alkanes in petrol. Write the equation for the complete combustion of heptane. State symbols are not required. ...................................................................................................................................... [2]
18. June 2023 · AS Paper 1 · Q25(a) · 2 marks · AO1
25 This question is about hydrocarbons. (a) The boiling points of 2 hydrocarbons are shown below. Hydrocarbon Boiling point / °C butane 0 pentane 36 Explain the difference in the boiling points of butane and pentane. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2]
19. June 2023 · AS Paper 1 · Q25(b) · 2 marks · AO3
(b) Butane reacts with bromine by radical substitution to form a mixture of organic products. The reaction needs UV radiation for the initiation stage. Write equations for the propagation stage that follows to form 2-bromobutane. Use skeletal formulae and ‘dots’ (•) to show the position of any radicals. Propagation [2]
20. June 2023 · Paper 2 · Q8 · 1 marks · AO2
8 For complete combustion, 0.100 mol of an alkane requires 22.8 dm3 of O2, measured at RTP. Which alkane has undergone complete combustion? A pentane B hexane C heptane D octane Your answer [1]
21. June 2023 · Paper 2 · Q16(a) · 4 marks · AO1
16 This question is about hydrocarbons. (a) The boiling points of some hydrocarbons containing 6 carbon atoms are shown below. Hydrocarbon Boiling point / ºC 2,2-dimethylbutane 50 2-methylpentane 60 hexane 69 State and explain the trend in boiling points shown by these hydrocarbons. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [4]
22. June 2023 · Paper 2 · Q16(b)(i) · 6 marks · AO1, 2, 3
(b) 2-methylpentane reacts with bromine by radical substitution. 2-methylpentane A mixture of organic products is formed, including 3-bromo-2-methylpentane, and compounds A and B. (i) Complete the table below to show the mechanism for the formation of 3-bromo-2-methylpentane and three possible equations for termination. In your equations, use structural or skeletal formulae and ‘dots’ (•) for the position of radicals. Equation: ............................................................................................ Initiation Conditions: ......................................................................................... Propagation Termination [6]
23. June 2023 · Paper 2 · Q16(b)(ii) · 2 marks · AO2
(ii) Organic compound A is formed by the substitution of all 14 H atoms in 2-methylpentane by Br atoms. Write the equation, using molecular formulae, for the formation of compound A from 2-methylpentane. ...................................................................................................................................... [2]
24. June 2022 · AS Paper 1 · Q14 · 1 marks · AO1
14 What is the number of σ-bonds in the molecule below? A 1 B 3 C 7 D 9 Your answer [1]
25. June 2022 · AS Paper 1 · Q16 · 1 marks · AO2
16 Complete combustion of an alkane forms 30 cm3 of carbon dioxide and 40 cm3 of water vapour, under the same conditions of temperature and pressure. Which alkane has undergone complete combustion? A butane B ethane C heptane D propane Your answer [1]
26. June 2022 · Paper 2 · Q3 · 1 marks · AO1
3 What is the number of sigma bonds in a molecule of methylbenzene? A 7 B 10 C 12 D 15 Your answer [1]
27. June 2022 · AS Paper 2 · Q5(a)(i) · 1 marks · AO1
5 2-Bromobutane, CH3CH2CHBrCH3, can be prepared by three different methods. The relative molecular mass, Mr, of 2-bromobutane is 136.9. (a) 2-Bromobutane can be prepared by reacting butane with bromine (Reaction 5.1). CH3CH2CH2CH3 + Br2 CH3CH2CHBrCH3 + HBr Reaction 5.1 The reaction is initiated by the formation of bromine radicals from bromine. (i) State the conditions for the formation of bromine radicals from bromine. ...................................................................................................................................... [1]
28. June 2022 · AS Paper 2 · Q5(a)(ii) · 2 marks · AO2
(ii) Write two equations for the propagation steps in the mechanism for Reaction 5.1. Use structural formulae for organic species and dots (•) for unpaired electrons on radicals. CH3CH2CH2CH3 + ................ ............................................... + ................ .............................................. + ................ ............................................... + ................ [2]
29. June 2022 · AS Paper 2 · Q5(a)(iii) · 2 marks · AO3
(iii) The yield of CH3CH2CHBrCH3 is only 30%. Suggest two reasons why the yield of CH3CH2CHBrCH3 is so low. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... [2]
30. June 2022 · Paper 2 · Q7 · 1 marks · AO1
7 Complete combustion of 0.050 mol of an alkane produces 5.40 g of H2O. What is the molecular formula of the alkane? A C2H6 B C3H8 C C4H10 D C5H12 Your answer [1]
31. June 2022 · Paper 2 · Q13 · 1 marks · AO1
13 Which equation(s) could be part of the propagation step in the radical substitution of C5H12 to form C5H11Cl ? 1 C5H11• + Cl 2 C5H11Cl + Cl • 2 C5H12 + Cl • C5H11Cl + H• 3 C5H11• + Cl • C5H11Cl A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
32. June 2022 · Paper 3 · Q5(b)(i) · 1 marks · AO2
(b) Internal combustion engines have historically used fuels obtained from crude oil as a source of power. The environmental effects of fossil fuel use can be reduced by blending petrol with biofuels such as ethanol. A fuel is being developed using a 1:1 molar ratio of octane and ethanol. (i) Write the equation for the complete combustion of this fuel. ...................................................................................................................................... [1]
33. November 2021 · AS Paper 1 · Q15 · 1 marks · AO2
15 Which structural isomer of C7H16 has the weakest induced dipole–dipole interactions (London forces)? A 2,3-dimethylpentane B 3-ethylpentane C 2-methylhexane D 2,2,3-trimethylbutane Your answer [1]
34. November 2021 · AS Paper 1 · Q16 · 1 marks · AO1
16 Which compound contains the smallest bond angle? A bromoethane B ethanol C ethane D ethene Your answer [1]
35. November 2021 · Paper 2 · Q1 · 1 marks ·
1 2-Methylbutane is reacted with chlorine by radical substitution. What is the number of structural isomers with the molecular formula C5H11Cl that could be formed? A 2 B 3 C 4 D 5 Your answer [1]
36. November 2021 · AS Paper 2 · Q2(c) · 2 marks · AO2
(c) In this reaction with bromine, monosubstitution of alkane A forms a mixture of organic products. Show the structures of two monosubstituted organic products that are formed. [2]
37. November 2021 · AS Paper 2 · Q2(d) · 2 marks · AO2
(d) With excess bromine, further substitution takes place. Write an equation for the reaction of alkane A with excess bromine to produce 1,3-dibromo-2-methylpropane. Use structures for the organic compounds. [2]
38. November 2021 · Paper 2 · Q4 · 1 marks ·
4 What is the correct equation for the incomplete combustion of butan-1-ol? A CH3CH2CH2CH2OH + 1½O2 4CO + 5H2 B CH3CH2CH2CH2OH + 2O2 4CO + 5H2 C CH3CH2CH2CH2OH + 4O2 4CO + 5H2O D CH3CH2CH2CH2OH + 4½O2 4CO + 5H2O Your answer [1]
39. November 2021 · Paper 2 · Q16(a)(i) · 2 marks · AO1
SECTION B Answer all the questions. 16 But-1-ene, H2C=CHCH2CH3, and buta-1,3-diene, H2C=CH–CH=CH2, are unsaturated compounds used to make many organic products. (a) But-1-ene and buta-1,3-diene have σ-bonds and π-bonds. (i) Explain what is meant by the terms σ-bond and π-bond. σ-bond: .............................................................................................................................. ........................................................................................................................................... π-bond: .............................................................................................................................. ........................................................................................................................................... [2]
40. November 2021 · Paper 2 · Q16(a)(ii) · 2 marks · AO1
(ii) How many σ- and π-bonds are in one molecule of buta-1,3-diene? σ-bonds: .................................................. π-bonds: .................................................. [2]
41. November 2020 · AS Paper 1 · Q15 · 1 marks · AO1
15 Which property explains the low reactivity of alkanes? A Electron pair repulsion between σ-bonds B Free rotation about σ-bonds C High C–C bond enthalpy D High polarity of the C–H bonds Your answer [1]
42. November 2020 · Paper 2 · Q16(c) · 3 marks · AO1, 2
(c) Complete the table to show the mechanism for the reaction of hydrocarbon A with Br2 to form (CH3)3CCHBrCH3. Use skeletal formulae for all organic compounds. Use ‘dots’ (●) to show the position of unpaired electrons. Initiation ...................................................................................................................................... Propagation + .............................. .............................. + .............................. .............................. + .............................. .............................. + .............................. [3]
43. November 2020 · Paper 2 · Q16(d) · 2 marks · AO1
(d) State two limitations of using radical substitution in organic synthesis. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... [2]
44. November 2020 · Paper 3 · Q1(b)(i) · 4 marks · AO1, 2
(b) This part is about amines. (i) The table shows the structures and boiling points of three amines, which are structural isomers of C3H9N. Amine CH3CH2CH2NH2 (CH3)2CHNH2 (CH3)3N Skeletal formula NH2 N NH2 Boiling point / °C 48–49 °C 33–34 °C 3–4 °C Explain the difference in the boiling points of the three amines. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [4]
45. June 2019 · AS Paper 1 · Q25(b)(i) · 3 marks · AO1, 2
(b) Under suitable conditions, butane, C4H10, reacts with chlorine by radical substitution. A mixture of organic compounds is formed, including C4H9Cl , and compounds D and E. (i) Complete the table below to show the mechanism for the initiation and propagation stages of the reaction of C4H10 with chlorine to form C4H9Cl . In your equations, use molecular formulae and ‘dots’ (•) with any radicals. Equation .................................................................................................... Initiation Conditions .................................................................................................. ..................................................... → ..................................................... Propagation ..................................................... → ..................................................... [3]
46. June 2019 · AS Paper 1 · Q25(b)(ii) · 1 marks · AO2
(ii) Organic compound D is formed by substitution of all the H atoms in butane by Cl atoms. Write the equation for the formation of compound D from butane. Use molecular formulae. ...................................................................................................................................... [1]
47. June 2019 · Paper 2 · Q1 · 1 marks · AO1
1 Which alkane has the highest boiling point? A CH3(CH2)5CH3 B (CH3)3CCH(CH3)2 C CH3(CH2)3CH(CH3)2 D (CH3)2CHCH2CH(CH3)2 Your answer [1]
48. June 2019 · Paper 2 · Q2 · 1 marks · AO2
2 Butane reacts with chlorine in the presence of ultraviolet radiation to form a mixture of organic products. Which equation shows a propagation step in the mechanism for this reaction? A Cl 2 → •Cl + •Cl B •Cl + •C4H8Cl → C4H8Cl 2 C C4H9Cl + •Cl → C4H8Cl 2 + •H D •Cl + C4H9Cl → •C4H8Cl + HCl Your answer [1]
49. June 2019 · Paper 2 · Q5 · 1 marks · AO2
5 Which types of bonds are broken and formed in the reaction of ethene and bromine? Types of bond broken Types of bond formed A σ π B π σ C σ and π π D σ and π σ Your answer [1]
50. June 2018 · AS Paper 1 · Q15 · 1 marks ·
15 1 mol of a compound reacts with 8 mol O2 for complete combustion. What is the formula of the compound? A C4H8 B C4H9OH C C5H11OH D C5H12 Your answer [1]
51. June 2018 · AS Paper 1 · Q24(a) · 5 marks ·
24 This question is about saturated hydrocarbons. (a) 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 the structures to explain what is meant by the term structural isomer. • Explain the trend in boiling points shown by A, B and C in the table. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [5]
52. June 2018 · AS Paper 1 · Q24(b)(i) · 1 marks ·
(b) Compounds A, B and C all react with chlorine in the presence of ultraviolet radiation to form organic compounds with the formula C5H11Cl. (i) Name the mechanism for this reaction. ...................................................................................................................................... [1]
53. June 2018 · AS Paper 1 · Q24(b)(ii) · 2 marks ·
(ii) Complete the table to show the number of structural isomers of C5H11Cl that could be formed from the reaction of chlorine with A and B. A B Number of structural isomers ...................... ...................... [2]
54. June 2018 · AS Paper 1 · Q24(b)(iii) · 2 marks ·
(iii) The reaction of compound A with excess chlorine forms a compound D, which has a molar mass of 175.5 g mol−1. Draw a possible structure for compound D and write the equation for its formation from compound A. Use molecular formulae in the equation. Compound D Equation ........................................................................................................................ [2]
55. June 2018 · Paper 2 · Q5 · 1 marks ·
5 Which molecule is not planar? A C2H4 B C2H6 C H2CO D HCN Your answer [1]
56. June 2018 · Paper 2 · Q22(a) · 1 marks ·
22 The relative molecular masses and boiling points of some fuels are shown in Table 22.1. Fuel Relative molecular mass Boiling point / °C hexane 86 69 pentan-1-ol 88 138 heptane 100 98 Table 22.1 (a) Write an equation for the incomplete combustion of heptane. .............................................................................................................................................. [1]
57. June 2018 · Paper 2 · Q22(b) · 4 marks ·
(b) Explain the difference in the boiling points of the fuels in Table 22.1. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [4]
58. June 2017 · AS Paper 1 · Q17 · 1 marks ·
17 Which organic compound has the lowest boiling point? A 2,3,4-trimethylpentane B 2,3-dimethylhexane C 2-methylheptane D octane Your answer [1]
59. June 2017 · AS Paper 2 · Q5(b)(i) · 2 marks ·
(b) The displayed formula for propanoic acid is shown below. H H O H C C C O H H H (i) State the shape and bond angle around a carbon atom in the alkyl group of propanoic acid. Explain the shape. Shape ................................................................................................................................ Bond angle ........................................................................................................................ Explanation ....................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
60. June 2017 · AS Paper 2 · Q5(d)(i) · 1 marks ·
(d) 2-Chloropropanoic acid, CH3CHClCOOH, can be made by reacting propanoic acid with chlorine in a radical substitution reaction. (i) State the conditions for the reaction. ...................................................................................................................................... [1]
61. June 2017 · AS Paper 2 · Q5(d)(ii) · 1 marks ·
(ii) Write the overall equation for the reaction. ...................................................................................................................................... [1]
62. June 2017 · AS Paper 2 · Q5(d)(iv) · 2 marks ·
(iv) Write two equations to show the propagation steps in the mechanism for this reaction. Use dots,•, to show the unpaired electrons on radicals. ........................................................................................................................................... ...................................................................................................................................... [2]
63. June 2017 · AS Paper 2 · Q5(d)(vi) · 1 marks ·
(vi) Further substitution forms a mixture of organic products. Draw the structure of an organic product formed from 2-chloropropanoic acid by further substitution. [1]
64. June 2017 · Paper 2 · Q14 · 1 marks ·
14 Ethane reacts with chlorine by radical substitution to form chloroethane. Which radical(s) is/are present in the mechanism? 1 H 2 Cl 3 C2H5 A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
65. June 2017 · Paper 2 · Q16(a) · 2 marks ·
SECTION B Answer all the questions. 16 This question is about unsaturated hydrocarbons. (a) Compound A and compound B are isomers. compound A compound B Compound A has a lower melting point than compound B. Suggest why. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2]
66. June 2017 · Paper 3 · Q1(e) · 1 marks ·
(e) Suggest why some industries are interested in the presence of ‘methane hydrate’ in regions of the Earth. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [1]
67. June 2016 · AS Paper 1 · Q16 · 1 marks ·
8 16 The displayed formula for a hydrocarbon is shown below. H H H C C C H H C C H H H How many σ and π bonds are present in a molecule of this hydrocarbon? σ bonds π bonds A 2 4 B 10 2 C 10 4 D 12 2 Your answer [1]
68. June 2016 · AS Paper 1 · Q17 · 1 marks ·
17 Chlorine reacts with 1-chloropropane in the presence of ultraviolet radiation via a radical substitution mechanism. Which equation shows a propagation step in the mechanism for this reaction? A Cl2 → •Cl + •Cl B •Cl + •C3H6Cl → C3H6Cl2 C C3H7Cl + •Cl → C3H6Cl2 + •H D •Cl + C3H7Cl → •C3H6Cl + HCl Your answer [1]
69. June 2016 · AS Paper 2 · Q3(a)(i) · 1 marks ·
6 3 Compound A is an alkene. H3C CH3 C C H CH3 compound A (a) The C=C bond in a molecule of compound A has restricted rotation because it comprises a σ bond and a π bond. (i) Describe one difference between the σ bond and the π bond. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]

Mark schemes

1. June 2025 · AS Paper 1 · Q24(b)
Mark scheme June 2025 Paper 1 Q24(b)
2. June 2025 · AS Paper 2 · Q4(a)
Mark scheme June 2025 Paper 2 Q4(a)
3. June 2025 · AS Paper 2 · Q4(b)(i)
Mark scheme June 2025 Paper 2 Q4(b)(i)
4. June 2025 · AS Paper 2 · Q4(d)(i)
Mark scheme June 2025 Paper 2 Q4(d)(i)
5. June 2025 · AS Paper 2 · Q4(d)(iii)
Mark scheme June 2025 Paper 2 Q4(d)(iii)
6. June 2025 · AS Paper 2 · Q4(d)(iv)
Mark scheme June 2025 Paper 2 Q4(d)(iv)
7. June 2025 · AS Paper 2 · Q5(a)(ii)
Mark scheme June 2025 Paper 2 Q5(a)(ii)
8. June 2025 · Paper 2 · Q16(b)
Mark scheme June 2025 Paper 2 Q16(b)
9. June 2025 · Paper 2 · Q16(d)
Mark scheme June 2025 Paper 2 Q16(d)
10. June 2024 · AS Paper 1 · Q16
Mark scheme June 2024 Paper 1 Q16
11. June 2024 · AS Paper 1 · Q24(a)
Mark scheme June 2024 Paper 1 Q24(a)
12. June 2024 · AS Paper 1 · Q24(b)
Mark scheme June 2024 Paper 1 Q24(b)
13. June 2024 · AS Paper 1 · Q24(c)
Mark scheme June 2024 Paper 1 Q24(c)
14. June 2024 · Paper 2 · Q4
Mark scheme June 2024 Paper 2 Q4
15. June 2024 · Paper 2 · Q18(a)(i)
Mark scheme June 2024 Paper 2 Q18(a)(i)
16. June 2024 · Paper 2 · Q18(a)(ii)
Mark scheme June 2024 Paper 2 Q18(a)(ii)
17. June 2023 · AS Paper 1 · Q23(a)(i)
Mark scheme June 2023 Paper 1 Q23(a)(i)
18. June 2023 · AS Paper 1 · Q25(a)
Mark scheme June 2023 Paper 1 Q25(a)
19. June 2023 · AS Paper 1 · Q25(b)
Mark scheme June 2023 Paper 1 Q25(b)
20. June 2023 · Paper 2 · Q8
Mark scheme June 2023 Paper 2 Q8
21. June 2023 · Paper 2 · Q16(a)
Mark scheme June 2023 Paper 2 Q16(a)
22. June 2023 · Paper 2 · Q16(b)(i)
Mark scheme June 2023 Paper 2 Q16(b)(i)
23. June 2023 · Paper 2 · Q16(b)(ii)
Mark scheme June 2023 Paper 2 Q16(b)(ii)
24. June 2022 · AS Paper 1 · Q14
Mark scheme June 2022 Paper 1 Q14
25. June 2022 · AS Paper 1 · Q16
Mark scheme June 2022 Paper 1 Q16
26. June 2022 · Paper 2 · Q3
Mark scheme June 2022 Paper 2 Q3
27. June 2022 · AS Paper 2 · Q5(a)(i)
Mark scheme June 2022 Paper 2 Q5(a)(i)
28. June 2022 · AS Paper 2 · Q5(a)(ii)
Mark scheme June 2022 Paper 2 Q5(a)(ii)
29. June 2022 · AS Paper 2 · Q5(a)(iii)
Mark scheme June 2022 Paper 2 Q5(a)(iii)
30. June 2022 · Paper 2 · Q7
Mark scheme June 2022 Paper 2 Q7
31. June 2022 · Paper 2 · Q13
Mark scheme June 2022 Paper 2 Q13
32. June 2022 · Paper 3 · Q5(b)(i)
Mark scheme June 2022 Paper 3 Q5(b)(i)
33. November 2021 · AS Paper 1 · Q15
Mark scheme November 2021 Paper 1 Q15
34. November 2021 · AS Paper 1 · Q16
Mark scheme November 2021 Paper 1 Q16
35. November 2021 · Paper 2 · Q1
Mark scheme November 2021 Paper 2 Q1
36. November 2021 · AS Paper 2 · Q2(c)
Mark scheme November 2021 Paper 2 Q2(c)
37. November 2021 · AS Paper 2 · Q2(d)
Mark scheme November 2021 Paper 2 Q2(d)
38. November 2021 · Paper 2 · Q4
Mark scheme November 2021 Paper 2 Q4
39. November 2021 · Paper 2 · Q16(a)(i)
Mark scheme November 2021 Paper 2 Q16(a)(i)
40. November 2021 · Paper 2 · Q16(a)(ii)
Mark scheme November 2021 Paper 2 Q16(a)(ii)
41. November 2020 · AS Paper 1 · Q15
Mark scheme November 2020 Paper 1 Q15
42. November 2020 · Paper 2 · Q16(c)
Mark scheme November 2020 Paper 2 Q16(c)
43. November 2020 · Paper 2 · Q16(d)
Mark scheme November 2020 Paper 2 Q16(d)
44. November 2020 · Paper 3 · Q1(b)(i)
Mark scheme November 2020 Paper 3 Q1(b)(i)
45. June 2019 · AS Paper 1 · Q25(b)(i)
Mark scheme June 2019 Paper 1 Q25(b)(i)
46. June 2019 · AS Paper 1 · Q25(b)(ii)
Mark scheme June 2019 Paper 1 Q25(b)(ii)
47. June 2019 · Paper 2 · Q1
Mark scheme June 2019 Paper 2 Q1
48. June 2019 · Paper 2 · Q2
Mark scheme June 2019 Paper 2 Q2
49. June 2019 · Paper 2 · Q5
Mark scheme June 2019 Paper 2 Q5
50. June 2018 · AS Paper 1 · Q15
Mark scheme June 2018 Paper 1 Q15
51. June 2018 · AS Paper 1 · Q24(a)
Mark scheme June 2018 Paper 1 Q24(a)
52. June 2018 · AS Paper 1 · Q24(b)(i)
Mark scheme June 2018 Paper 1 Q24(b)(i)
53. June 2018 · AS Paper 1 · Q24(b)(ii)
Mark scheme June 2018 Paper 1 Q24(b)(ii)
54. June 2018 · AS Paper 1 · Q24(b)(iii)
Mark scheme June 2018 Paper 1 Q24(b)(iii)
55. June 2018 · Paper 2 · Q5
Mark scheme June 2018 Paper 2 Q5
56. June 2018 · Paper 2 · Q22(a)
Mark scheme June 2018 Paper 2 Q22(a)
57. June 2018 · Paper 2 · Q22(b)
Mark scheme June 2018 Paper 2 Q22(b)
58. June 2017 · AS Paper 1 · Q17
Mark scheme June 2017 Paper 1 Q17
59. June 2017 · AS Paper 2 · Q5(b)(i)
Mark scheme June 2017 Paper 2 Q5(b)(i)
60. June 2017 · AS Paper 2 · Q5(d)(i)
Mark scheme June 2017 Paper 2 Q5(d)(i)
61. June 2017 · AS Paper 2 · Q5(d)(ii)
Mark scheme June 2017 Paper 2 Q5(d)(ii)
62. June 2017 · AS Paper 2 · Q5(d)(iv)
Mark scheme June 2017 Paper 2 Q5(d)(iv)
63. June 2017 · AS Paper 2 · Q5(d)(vi)
Mark scheme June 2017 Paper 2 Q5(d)(vi)
64. June 2017 · Paper 2 · Q14
Mark scheme June 2017 Paper 2 Q14
65. June 2017 · Paper 2 · Q16(a)
Mark scheme June 2017 Paper 2 Q16(a)
66. June 2017 · Paper 3 · Q1(e)
Mark scheme June 2017 Paper 3 Q1(e)
67. June 2016 · AS Paper 1 · Q16
Mark scheme June 2016 Paper 1 Q16
68. June 2016 · AS Paper 1 · Q17
Mark scheme June 2016 Paper 1 Q17
69. June 2016 · AS Paper 2 · Q3(a)(i)
Mark scheme June 2016 Paper 2 Q3(a)(i)