Lesson 6C.2

6C.2 Electrophilic addition mechanisms and tests Quiz: Pearson Edexcel Chemistry, Unit 6

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 6C.2, Electrophilic addition mechanisms and tests: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 6: Organic Chemistry I, written with Revision Ninja.

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The 20 questions

  1. Which term best describes the role of an electrophile?

    • Electron pair donor
    • Free radical generator
    • Proton acceptor
    • Electron pair acceptor

  2. What type of bond fission occurs when ethene reacts with bromine?

    • Homolytic fission
    • Thermal fission
    • Heterolytic fission
    • Photolytic fission

  3. Where does a curly arrow start in an organic reaction mechanism?

    • Reaction product
    • Electron pair
    • Atomic nucleus
    • Positively charged atom

  4. What is the intermediate formed in the electrophilic addition of Br2 to ethene?

    • A carbocation, CH2BrCH2+
    • A carbanion, CH2BrCH2-
    • An ester, CH2BrCOOCH3
    • A free radical, CH2BrCH2*

  5. What colour change occurs when bromine water reacts with an alkene?

    • Orange to colourless
    • Blue to red
    • Colourless to orange
    • Purple to colourless

  6. Why do alkanes not decolourise bromine water in the dark?

    • No sigma bonds
    • High polarity
    • No pi bond
    • Too reactive

  7. Propene reacts with hydrogen bromide. What is the major product?

    • 2-bromopropane
    • Bromoethane
    • 1,2-dibromopropane
    • 1-bromopropane

  8. Which type of carbocation is the most stable?

    • Tertiary
    • Methyl
    • Secondary
    • Primary

  9. Why are secondary carbocations more stable than primary carbocations?

    • Electronegativity
    • Inductive effect
    • Hydrogen bonding
    • Steric hindrance

  10. What is the major product when 2-methylpropene reacts with hydrogen chloride?

    • 2-chloro-2-methylpropane
    • 2-chloropropane
    • 1,2-dichloro-2-methylpropane
    • 1-chloro-2-methylpropane

  11. Which atom acts as the electrophile in HBr addition to ethene?

    • Carbon atom
    • Bromine atom
    • Bromide ion
    • Hydrogen atom

  12. What intermediate is formed in the first step of electrophilic addition of HCl to ethene?

    • Carbocation
    • Transition state
    • Free radical
    • Carbanion

  13. Which compound forms as the major product when but-2-ene reacts with HBr?

    • 2-methylpropyl bromide
    • 2-bromobutane
    • 1-bromobutane
    • 1,2-dibromobutane

  14. Which intermediate is formed when propene reacts with H+ in the first step of hydration?

    • A secondary carbocation, CH3CH+CH3
    • A carbanion, CH3CH-CH3
    • A primary carbocation, CH3CH2CH2+
    • A radical, CH3CH*CH3

  15. What is the expected colour change of acidified potassium manganate(VII) when reacted with an alkene?

    • Blue to pink
    • Colourless to green
    • Yellow to orange
    • Purple to colourless

  16. What is the correct name for the product of Br2 with but-1-ene?

    • 1,1-dibromobutane
    • 2,3-dibromobutane
    • 1,4-dibromobutane
    • 1,2-dibromobutane

  17. Why is the reaction of ethene with bromine classified as addition rather than substitution?

    • Hydrogen atoms substituted
    • No atoms eliminated
    • Carbon chain shortened
    • Double bond formed

  18. What factor determines the regioselectivity of electrophilic addition to an unsymmetrical alkene?

    • Electronegativity difference
    • Electrophile size
    • Carbocation stability
    • Bond enthalpy

  19. What effect from attached alkyl groups stabilises a tertiary carbocation?

    • Inductive effect
    • Resonance effect
    • Steric effect
    • Hydrogen bonding

  20. What is the major product when propene reacts with aqueous bromine?

    • 1-bromopropan-2-ol
    • 2-bromopropan-1-ol
    • 1,2-dibromopropane
    • 2-bromopropane

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