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Practice · Chemistry · 2025 syllabus · R3.2

IB Chemistry R3.2 Electron transfer reactions: practice questions

13 exam-style questions on R3.2 Electron transfer reactions, SL and HL, 5 marked HL: 8 multiple choice, 1 data-based and 4 structured. Each one comes with the mark scheme, a model answer and the reasoning behind every mark. Free with your email.

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R3.2-01 · Paper 1A style · multiple choice · 1 mark

Chlorine in the +3 state

In which species does chlorine have an oxidation state of +3? [1]

  1. Cl2O
  2. ClO3−
  3. ClO2−
  4. HClO4
Show the answer and the reasoning

Answer: C. C is correct. In ClO2−: x + 2(−2) = −1, so x = +3. A: 2x − 2 = 0, x = +1. B: x − 6 = −1, x = +5. D: +1 + x − 8 = 0, x = +7. Oxygen is −2 and hydrogen +1, and the total equals the charge on the species.

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The 13 questions in R3.2

  1. R3.2-01 Chlorine in the +3 statePaper 1A style · multiple choice · 1 mark
  2. R3.2-02 Oxidizing and reducing agentsPaper 1A style · multiple choice · 1 mark
  3. R3.2-03 Balancing a reduction half-equationPaper 1A style · multiple choice · 1 mark
  4. R3.2-04 Order of reactivity from displacementPaper 1A style · multiple choice · 1 mark
  5. R3.2-05 Standard cell potentialPaper 1A style · multiple choice · 1 mark · HL
  6. R3.2-06 Electrolysis of aqueous potassium iodidePaper 1A style · multiple choice · 1 mark · HL
  7. R3.2-07 Which alcohols oxidizePaper 1A style · multiple choice · 1 mark
  8. R3.2-08 Reducing a ketonePaper 1A style · multiple choice · 1 mark
  9. R3.2-09 Vitamin C by iodine titrationPaper 1B style · data-based · 7 marks
  10. R3.2-10 Dichromate oxidizing iron(II)Paper 2 style · structured question · 5 marks
  11. R3.2-11 A magnesium–copper cellPaper 2 style · structured question · 6 marks · HL
  12. R3.2-12 Electrolysis and electroplatingPaper 2 style · structured question · 5 marks · HL
  13. R3.2-13 Lithium and rechargeable cellsPaper 2 style · structured question · 5 marks · HL

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Every Biology and Chemistry question here is original, written for practice in the style of the papers set since the 2025 syllabus, with invented data. Developed independently from the International Baccalaureate Organization, which has not endorsed it. Found a mistake? Email vytis@limeadmissions.com with the question id.