Lesson 5.7.1.4

5.7.1.4 Cracking and alkenes Quiz: AQA Combined Science, Unit 14

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.7.1.4, Cracking and alkenes: 20 multiple choice questions for the AQA GCSE Combined Science (8464), Unit 14: Organic chemistry, written with Revision Ninja.

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The 20 questions

  1. What is the main purpose of cracking large hydrocarbons?

    • Increasing chain length
    • Removing all hydrogen
    • Creating crude oil
    • Producing smaller molecules

  2. What are the two main industrial methods used for cracking hydrocarbons?

    • Thermal and fractional
    • Catalytic and steam
    • Oxidation and reduction
    • Addition and condensation

  3. What are the two types of products formed when hydrocarbons are cracked?

    • Alkanes and alcohols
    • Monomers and polymers
    • Alkenes and polymers
    • Alkanes and alkenes

  4. What is the colour change when an alkene reacts with bromine water?

    • Orange to colourless
    • Blue to colourless
    • Colourless to orange
    • Orange to green

  5. Compared with alkanes, alkenes are:

    • Inert
    • More reactive
    • Equally reactive
    • Less reactive

  6. High demand for small molecules means some cracking products are used as:

    • Fuels
    • Fertilisers
    • Food
    • Catalysts

  7. Alkenes are used to produce:

    • Polymers
    • Nitrogen gas
    • Metals
    • Oxygen gas

  8. Which equation for cracking is balanced?

    • C8H18 gives C4H8 + C4H10
    • C8H18 gives C4H8 + C4H12
    • C8H18 gives C4H8 + C4H9
    • C8H18 gives C4H8 + C3H10

  9. Cracking C10H22 gives C2H4 and another product. The other product is:

    • C8H18
    • C10H20
    • C8H20
    • C8H16

  10. What happens when bromine water is added to an alkane?

    • no colour change
    • turns green
    • turns colourless
    • turns purple

  11. Which conditions are used in steam cracking of hydrocarbons?

    • High temperature
    • High pressure only
    • Room temperature
    • Low temperature

  12. Which conditions are used in catalytic cracking?

    • Enzymes
    • No catalyst
    • Cold catalyst
    • Hot catalyst

  13. What are alkenes mainly used to produce?

    • Crude oil
    • Polymers
    • Noble gases
    • Mineral acids

  14. Why is cracking hydrocarbons economically useful?

    • creates heavy solids
    • reduces fuel supply
    • removes all alkenes
    • meets fuel demand

  15. What type of chemical bond is broken during the cracking process?

    • C-C bonds
    • C=O bonds
    • O-H bonds
    • C-H bonds

  16. Ethene has the formula:

    • C2H8
    • C2H4
    • C2H6
    • C2H2

  17. Cracking C6H14 gives C3H6 and another product. The other product is:

    • C3H10
    • C3H8
    • C6H12
    • C3H6

  18. What type of substance is primarily used as the starting material for cracking?

    • Small alkenes
    • Long-chain hydrocarbons
    • Polymer chains
    • Carbon dioxide

  19. What are the products of cracking mainly used as?

    • insoluble salts
    • fuels and polymers
    • lubricants only
    • mineral ores

  20. What major industrial problem does the cracking process solve?

    • Low reactivity of alkanes
    • Supply and demand mismatch
    • Excessive alkene production
    • Low boiling points

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