Lesson 6D.2

6D.2 Nucleophilic substitution and reactivity trends Quiz: Pearson Edexcel Chemistry, Unit 6

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 6D.2, Nucleophilic substitution and reactivity trends: 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 halogenoalkane is the most reactive towards hydrolysis in aqueous silver nitrate?

    • 1-bromobutane, a primary bromoalkane in which the bromine is on the first carbon of the chain
    • 2-bromobutane, a secondary bromoalkane in which the bromine sits on an internal carbon atom
    • 2-iodo-2-methylpropane
    • 1-chlorobutane, a primary chloroalkane in which the chlorine is bonded to a terminal carbon atom

  2. Which statement explains why iodoalkanes react faster than chloroalkanes?

    • Iodine is less electronegative than chlorine, so it stops the nucleophile from attacking
    • The C-I bond has a lower bond enthalpy than the C-Cl bond, so it breaks more easily
    • The C-I bond is stronger, so more energy is released when it forms
    • Chloroalkanes contain more carbon atoms than iodoalkanes

  3. Approximately what is the mean bond enthalpy of the C-Cl bond, in kJ mol-1?

    • 340
    • 240
    • 280
    • 410

  4. Which mechanism describes the reaction of a primary halogenoalkane with aqueous hydroxide ions?

    • Electrophilic addition, via a bromonium ion
    • Radical substitution, via initiation and termination
    • Elimination, forming a carbocation followed by proton loss
    • Nucleophilic substitution, SN2, in a single concerted step

  5. In the SN2 mechanism of bromoethane with hydroxide, which curly arrow is correct?

    • From the lone pair on OH- to the carbon atom, and from the C-Br bond to the bromine
    • From the carbon to the hydroxide ion, forming a C-O bond with no electrons
    • From the bromine atom to the carbon, with no electron pair
    • From the C=C bond to the hydrogen atom

  6. Why are primary halogenoalkanes more readily substituted by SN2 than tertiary ones?

    • Tertiary halogenoalkanes contain no carbon-halogen bonds
    • The C-X bond in a primary halogenoalkane is stronger
    • The carbon is less hindered, so the nucleophile can approach it more easily
    • Primary halogenoalkanes always form carbocations as intermediates

  7. Why does the C-F bond not react readily in nucleophilic substitution?

    • Fluorine is always a catalyst in substitution reactions and so is never removed from the molecule
    • Fluorine is too large to be attacked by a nucleophile, because its atomic radius blocks the approach
    • Fluorine is a radical and does not form stable bonds, so it cannot be substituted by any nucleophile
    • The C-F bond is very strong, so it has a high bond enthalpy and is hard to break

  8. In a silver nitrate test, precipitate forms in 25 s for one halogenoalkane. Which quantity is used to compare relative rates?

    • The reciprocal of the time, 1/t
    • The volume of ethanol used only
    • The mass of the precipitate only
    • The temperature of the bath only

  9. Which species is the nucleophile in the reaction of 1-bromobutane with ammonia?

    • H+, from the ammonia molecule
    • NH3, through its lone pair on nitrogen
    • The butyl carbon, with its partial positive charge
    • Br-, through its lone pair

  10. Why does the reaction of a primary halogenoalkane with excess ammonia give a mixture of amines?

    • Ammonia is a radical that forms several products when it reacts with the halogenoalkane in the flask
    • The primary amine formed is itself a nucleophile and can react further with the halogenoalkane
    • The halide ion attacks the nitrogen atom to form a salt that precipitates out of the reaction mixture
    • Hydrogen is released as a gas, which leads to several different products being formed in the reaction

  11. Which factor makes tertiary halogenoalkanes react faster in hydrolysis by SN1 than primary ones?

    • Tertiary compounds have no hydrogen atoms that could be attacked
    • Tertiary halogenoalkanes are more soluble in silver nitrate
    • The carbocation intermediate formed is more stable with three alkyl groups
    • The C-X bond is weaker only in tertiary compounds

  12. Which of the following is the correct order of increasing rate of hydrolysis for CH3CH2Cl, CH3CH2Br and CH3CH2I?

    • CH3CH2Br < CH3CH2Cl < CH3CH2I
    • CH3CH2I < CH3CH2Br < CH3CH2Cl
    • All three react at the same rate
    • CH3CH2Cl < CH3CH2Br < CH3CH2I

  13. Which statement correctly describes the transition state in an SN2 reaction?

    • A radical pair is formed and then recombines
    • The nucleophile and leaving group are both partly bonded to the carbon
    • A full carbocation is formed and then attacked by the nucleophile
    • The C-X bond is already fully broken before the nucleophile arrives

  14. Which halogenoalkane would give the fastest precipitate with silver nitrate in ethanol at room temperature?

    • 2-bromobutane, a secondary bromoalkane in which the bromine sits on an internal carbon atom
    • 2-iodo-2-methylpropane
    • 1-bromobutane, a primary bromoalkane in which the bromine is on the first carbon of the chain
    • 1-chlorobutane, a primary chloroalkane in which the chlorine is bonded to a terminal carbon atom

  15. What is the effect of increasing bond polarity on the rate of nucleophilic substitution, compared with bond strength?

    • Polarity has no influence on nucleophilic substitution
    • Bond enthalpy usually controls the rate more than polarity, so weaker C-X bonds react faster
    • Greater polarity always makes the reaction slower by strengthening the bond
    • The most polar bond is always the least reactive

  16. Which statement describes the leaving group in nucleophilic substitution of a halogenoalkane?

    • The nucleophile, which is removed from the carbon
    • The carbocation, which is expelled from the molecule
    • The hydrogen atom attached to carbon
    • The halide ion, which takes the electron pair from the C-X bond

  17. Which halogenoalkane shows the greatest tendency to undergo SN1 in hydrolysis?

    • 1-bromopropane, a primary bromoalkane whose carbon bearing bromine is bonded to only one other carbon atom
    • Bromomethane, the simplest bromoalkane, in which the bromine is attached to a single carbon atom
    • 1-bromobutane, a primary bromoalkane in which the bromine sits at the end of a four-carbon chain
    • 2-bromo-2-methylpropane

  18. Which bond enthalpy values are in the correct order from strongest to weakest?

    • C-Br, C-Cl, C-I
    • C-I, C-Cl, C-Br
    • C-I, C-Br, C-Cl
    • C-Cl, C-Br, C-I

  19. A silver nitrate test takes 50 s for one halogenoalkane and 25 s for another under the same conditions. How many times faster is the second reaction?

    • The same rate
    • Twice as fast
    • Four times as fast
    • Half as fast

  20. What is the role of ethanol in the silver nitrate test for halogenoalkanes?

    • It acts as a catalyst that is consumed in the reaction and must be replenished during the test
    • It reacts with silver ions to remove them from solution so that no precipitate can form at all
    • It acts as the nucleophile that replaces the halogen atom and forms the alcohol product of the test
    • It dissolves the organic halogenoalkane, which is poorly soluble in water, so the reaction can proceed in one phase

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