plumiModification of alkanes by cracking: AQA A‑Level Chemistry questions
AQA A-Level Chemistry past-paper questions on 3.3.2.2 Modification of alkanes by cracking, 2008–2025, with mark schemes and examiner’s reports where available.
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All 40 questions on Modification of alkanes by cracking, as a list
- June 2025, Paper 3, Q28 (1 mark): Alkanes are obtained from crude oil by fractional distillation. Which statement is correct? [1 mark] A Alkanes obtained are converted to alkenes by thermal crac
- June 2025, AS Paper 2, Q10 (1 mark): Which statement about catalytic cracking is correct? [1 mark] A A high percentage of alkenes is formed. B A pressure of about 70 MPa is used. C C–C bonds are br
- June 2024, Paper 2, Q03.1 (2 marks): Eicosane (C20H42) can be cracked by heating to 700 K in the presence of a catalyst. The products are • an aromatic hydrocarbon C8H10 • an alkane C6H14 • another
- June 2024, Paper 2, Q03.3 (1 mark): Cracking can also be done without a catalyst, using a temperature of 1200 K and a pressure of 7000 kPa State the type of product that is formed in high percenta
- June 2024, AS Paper 2, Q16 (1 mark): Octadecane is a straight-chain alkane containing 18 carbon atoms per molecule. It is cracked to produce oct-1-ene and two other compounds. Which equation repres
- June 2023, AS Paper 2, Q02.2 (1 mark): Petrol for cars contains branched and cyclic alkanes produced by catalytic cracking. Identify the catalyst used in this process. [1 mark]
- June 2022, Paper 3, Q05.1 (2 marks): Zeolites are used as heterogeneous catalysts in the catalytic cracking of alkanes. Tetradecane (C14H30) can be cracked to form octane and a cycloalkane. Give an
- June 2022, AS Paper 2, Q08 (1 mark): When hexadecane (C16H34) is heated to a high temperature, one molecule of hexadecane decomposes to form an alkane containing eight carbon atoms and two differen
- November 2021, Paper 2, Q02.2 (3 marks): Hexadecane (C16H34) can be cracked at high temperature to form petrol. Complete the equation to show the cracking of one molecule of hexadecane to form hexane a
- November 2021, AS Paper 2, Q05.1 (6 marks): The three key steps in the manufacture of poly(propene) from crude oil are shown. Naphtha is a mixture of alkanes with 6 to 12 carbon atoms per molecule. For ea
- November 2020, AS Paper 2, Q09 (1 mark): Which statement is correct about thermal cracking? [1 mark] A A pressure between 100 and 200 kPa is used. B Aromatic hydrocarbons are the major products. C C–C
- June 2018, Paper 2, Q01.2 (3 marks): Heptane can be obtained from the catalytic cracking of hexadecane (C16H34) at a high temperature. Identify a suitable catalyst for this process. Give one condit
- June 2018, AS Paper 2, Q04.5 (1 mark): Nonane can be cracked to form large quantities of propene. Name the type of cracking used. [1 mark]
- June 2017, Paper 3, Q08 (1 mark): The table shows possible conditions and products for the cracking of alkanes. Which row is correct? [1 mark] Type of cracking Conditions Products A Thermal High
- June 2016, AS Paper 2, Q17 (1 mark): Tetradecane (C14H30) is an alkane found in crude oil. When tetradecane is heated to a high temperature, one molecule of tetradecane decomposes to form one molec
- Specimen, Paper 2, Q03.3 (1 mark): Isooctane can be formed, together with propene and ethene, in a reaction in which one molecule of an alkane that contains 20 carbon atoms is cracked. Using mole
- Specimen, Paper 2, Q03.4 (1 mark): How do the products of the reaction in Question 3.3 show that the reaction is an example of thermal cracking? [1 mark] 0 3 . 4
- June 2016, CHEM1 (old spec), Q4(b)(ii) (1 mark): One molecule of an alkane is cracked to produce one molecule of compound X, one molecule of octane and one molecule of ethene. Deduce the molecular formula of t
- June 2016, CHEM1 (old spec), Q4(b)(iii) (2 marks): Name the type of cracking that produces a high yield of compound X. Give two conditions required for this process. [2 marks] Type of cracking Conditions
- June 2015, CHEM1 (old spec), Q6(d)(i) (1 mark): Write an equation to show this cracking reaction. [1 mark]
- June 2014, CHEM1 (old spec), Q5(d)(ii) (3 marks): Write an equation for the cracking of one molecule of dodecane into equal amounts of two different molecules each containing the same number of carbon atoms. St
- June 2013, CHEM1 (old spec), Q2(c)(i) (1 mark): Deduce the molecular formula of Y. (1 mark)
- January 2013, CHEM1 (old spec), Q4(h)(i) (1 mark): Deduce the molecular formula of Z. (1 mark)
- January 2013, CHEM1 (old spec), Q4(h)(ii) (2 marks): State the type of cracking that produces a high proportion of ethene and propene. Give the two conditions for this cracking process. Type of cracking Conditions
- June 2012, CHEM1 (old spec), Q2(c)(i) (1 mark): Write an equation for this reaction. (1 mark)
- June 2012, CHEM1 (old spec), Q2(c)(ii) (2 marks): State the name of the process used to obtain a high yield of X from C15H32 Give one reason why this process is used in industry. Name Reason (2 marks)
- June 2012, CHEM1 (old spec), Q2(c)(iii) (1 mark): State why high temperatures are needed for this process. (1 mark)
- January 2012, CHEM1 (old spec), Q3(c)(i) (1 mark): Deduce the molecular formula of X. (1 mark)
- January 2012, CHEM1 (old spec), Q3(c)(ii) (2 marks): State the type of cracking that produces a high percentage of alkenes. State the conditions needed for this type of cracking. Type of cracking Conditions (2 mar
- January 2012, CHEM1 (old spec), Q3(c)(iii) (1 mark): Explain the main economic reason why alkanes are cracked. (1 mark)
- June 2011, CHEM1 (old spec), Q7(c) (3 marks): A molecule of hydrocarbon Y can be thermally cracked to form one molecule of pentane and two molecules of ethene only. Deduce the molecular formula of Y. State
- January 2011, CHEM1 (old spec), Q4(d)(i) (1 mark): State one condition that is used in this cracking reaction. (1 mark)
- January 2011, CHEM1 (old spec), Q4(d)(ii) (1 mark): Write an equation to show how one molecule of cetane can be cracked to form hexane, butene and ethene. (1 mark)
- June 2010, CHEM1 (old spec), Q6(c) (2 marks): The cracking of one molecule of compound X produces pent-1-ene, ethene and butane in a 1:2:1 mol ratio. Deduce the molecular formula of X and state a use for th
- January 2010, CHEM1 (old spec), Q4(d)(i) (1 mark): Write an equation for this cracking reaction. (1 mark)
- January 2010, CHEM1 (old spec), Q4(d)(ii) (1 mark): Suggest a type of compound that can be manufactured from the other product of this cracking reaction. (1 mark)
- January 2010, CHEM1 (old spec), Q4(d)(iii) (1 mark): State why a high temperature is needed for cracking reactions to occur. (1 mark)
- January 2009, CHEM1 (old spec), Q6(c) (4 marks): 6 (c) C8H18 is obtained by the catalytic cracking of suitable heavy fractions. State what is meant by the term cracking and name the catalyst used in catalytic
- June 2008, CHM3W (2008 spec), Q6(b) (3 marks): 6 (b) Give the name of the process by which ethene is produced from the naphtha fraction. Give one essential condition for this process and name the type of rea
- January 2008, CHM3W (2008 spec), Q4(c) (2 marks): (c) Write an equation for the catalytic cracking of dodecane (C12H26) to form cyclohexane and one other alkane. Identify the catalyst used in this reaction. Equ
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