Unit 6: Reactivity 3: What Are the Mechanisms of Chemical Change?

Topic 6.4: Electron-Pair Sharing Reactions Questions

Practice 20 exam-style questions for IB Chemistry Topic 6.4. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.

1State1 mark
2026
State the conditions needed for the hydrolysis of a halogenoalkane to an alcohol.
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2Identify1 mark
Identify the electrophile responsible for the nitration of benzene.
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3State1 mark
2026
State the reagent and condition used to distinguish an alkene from an alkane.
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4Explain1 mark
2026
Explain why 2-bromopropane is the major product.
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5Outline3 marks
Ethene, C₂H₄, reacts with bromine, Br₂, at room temperature.

Predict the organic product, state the type of reaction, and outline, with reference to electron-pair movement, why ethene readily undergoes this reaction. [3]
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6Explain3 marks
2-bromopropane, CH₃CHBrCH₃, is heated with warm aqueous potassium hydroxide.

State the type of reaction taking place, identify the organic product, and explain why an iodoalkane would react faster than this bromoalkane. [3]
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7state3 marks
State the type of reaction and the product when ethene reacts with bromine, and explain what is observed.
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8explain3 marks
Explain why alkenes undergo addition reactions readily but alkanes do not.
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9state3 marks
State the product when propene reacts with hydrogen bromide, and explain why two products are possible.
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10state3 marks
State the reagent and conditions for converting ethene into ethanol, and name the type of reaction.
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11state3 marks
State the reagent and conditions for converting bromoethane into ethanol, name the mechanism, and give the organic product.
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12explain3 marks
Define a nucleophile and explain why the hydroxide ion attacks the carbon atom of the C-Br bond in bromoethane.
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13explain3 marks
Explain why iodoethane undergoes nucleophilic substitution faster than chloroethane.
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14describe3 marks
Describe the mechanism of the reaction between bromoethane and the hydroxide ion, naming the bond that breaks and the bond that forms.
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15Explain3 marks
Two unlabelled samples are known to be propane and propene.

Describe a simple chemical test that distinguishes them, stating the observation for each, and explain why only one reacts. [3]
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16Deduce1 mark
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Deduce the organic product and name the mechanism.
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17Explain2 marks
Explain why the nitration of benzene requires a catalyst of concentrated sulfuric acid.
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18Predict1 mark
2026
What is the major product when hydrogen bromide adds to propene?
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19Outline1 mark
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Outline why alkenes are more reactive than alkanes.
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20Describe3 marks
Bromoethane, CH₃CH₂Br, is warmed with aqueous sodium hydroxide and undergoes nucleophilic substitution.

Use curly arrows to describe the movement of electron pairs in this reaction, and identify the leaving group. [3]
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