Lesson 4.1.3

4.1.3 Alkenes Quiz: OCR Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.1.3, Alkenes: 20 multiple choice questions for the OCR Chemistry (H432), Unit 3: Core organic chemistry, written with Revision Ninja.

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The 20 questions

  1. How is a pi bond in an alkene formed?

    • End-on orbital overlap
    • Electrostatic attraction
    • Direct electron transfer
    • Sideways orbital overlap

  2. What is the shape around each carbon atom in a C=C double bond?

    • Linear
    • Tetrahedral
    • Trigonal planar
    • Pyramidal

  3. What prevents free rotation around the C=C double bond in an alkene?

    • Sigma bond overlap
    • Hydrogen bonding
    • London forces
    • Pi bond overlap

  4. What structural feature is required on each double-bonded carbon for E/Z isomerism?

    • Two different groups
    • Three different groups
    • Two identical groups
    • One single group

  5. Which name matches cis-but-2-ene?

    • 2-methylpropene
    • But-1-ene
    • Z-but-2-ene
    • E-but-2-ene

  6. Which compound shows E/Z isomerism?

    • CH2=CH2
    • CH2=CCl2
    • CH2=CHCH3
    • CH3CH=CHCH3

  7. Which group has higher CIP priority on an alkene carbon: -Cl or -CH3?

    • Equal priority
    • -CH3
    • -Cl
    • Neither group

  8. What feature of alkenes makes them more reactive than alkanes?

    • Symmetrical shape
    • Low pi bond enthalpy
    • Non-polar structure
    • High sigma bond strength

  9. How is an electrophile defined in organic reaction mechanisms?

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

  10. Which catalyst is used to hydrogenate an alkene to an alkane?

    • Calcium carbonate
    • Sodium chloride
    • Nickel
    • Sulfuric acid

  11. What colour change is observed when bromine water reacts with an alkene?

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

  12. What is the major product of adding HBr to propene?

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

  13. Why does the reaction of propene with hydrogen bromide mainly form 2-bromopropane?

    • Steric hindrance
    • More stable carbocation
    • Lower bond enthalpy
    • Less stable carbocation

  14. Which catalyst is used to manufacture ethanol from ethene and steam?

    • Sodium hydroxide
    • Nickel
    • Phosphoric acid
    • Concentrated sulfuric acid

  15. What is the repeat unit of poly(propene)?

    • -CH2-CH2-
    • -CH2-CH2-CH3-
    • -CH2-CH(CH3)-
    • -CH(CH3)-CH(CH3)-

  16. What is the monomer of the polymer section -CH2-CHCl-CH2-CHCl-?

    • 1-chloropropene
    • 1,2-dichloroethane
    • Chloroethene
    • Chloromethane

  17. How is toxic hydrogen chloride gas removed during the incineration of PVC waste?

    • Scrubbing with alkali
    • Fractional distillation
    • Catalytic oxidation
    • Filtering with carbon

  18. What is a major environmental advantage of using biodegradable polymers?

    • Prevents recycling processes
    • Reduces persistent waste
    • Increases carbon footprint
    • Requires toxic catalysts

  19. How many moles of H2 are needed to fully hydrogenate 0.20 mol of but-1-ene?

    • 0.40 mol
    • 0.10 mol
    • 0.20 mol
    • 0.80 mol

  20. Which feature of the C=C double bond attracts an electrophile in addition reactions?

    • Non-polar C-H bond
    • Electron-deficient sigma bond
    • Electron-rich pi bond
    • Positively charged carbon

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