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O Level Chemistry: Redox, questions with answers

Practise 19 real questions on Redox from 2021 to 2025. See the answer and explanation as soon as you answer.

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19real questions
18multiple choice
9exam sessions

About Redox in O Level Chemistry

Redox is one of the 12 main topics in our O Level Chemistry (Cambridge (CAIE) 5070) question bank, and about 3% of its real questions come from it. Tayyari Karo has 19 real questions on this topic from 2021 to 2025, from Paper 1, Paper 2; 18 are multiple choice and marked instantly, and the rest are structured questions with a model answer.

Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.

Try 6 real questions

These are real past-paper questions. Think of your answer first, then open the explanation.

May/June 2025 · Paper 1 · Redox

In CuO + H2 -> Cu + H2O, H2 is

  1. oxidised
  2. reduced
  3. catalyst
  4. unchanged
Show answer and explanation

Answer: A. oxidised

H2 loses electrons.

May/June 2024 · Paper 1 · Redox

Zn + Cu2+ -> Zn2+ + Cu: oxidised?

  1. Zn
  2. Cu2+
  3. Zn2+
  4. Cu
Show answer and explanation

Answer: A. Zn

Zn loses electrons.

Oct/Nov 2024 · Paper 1 · Redox

O2 is

  1. oxidised
  2. reduced
  3. neutral
  4. catalyst
Show answer and explanation

Answer: B. reduced

Gains electrons.

Oct/Nov 2023 · Paper 1 · Redox

In 2KI + Cl2 -> I2 + 2KCl, chlorine is

  1. oxidised
  2. reduced
  3. catalyst
  4. neutral
Show answer and explanation

Answer: B. reduced

Cl2 gains electrons -> reduced.

May/June 2022 · Paper 1 · Redox

Rusting of iron requires

  1. oxygen only
  2. water only
  3. oxygen and water
  4. acid only
Show answer and explanation

Answer: C. oxygen and water

Both O₂ and H₂O cause rust.

May/June 2021 · Paper 1 · Redox

Which change in underlined species is oxidation? 1 CH₄→CO₂; 2 H₂S→S; 3 BrO₃⁻→Br₂.

  1. 1 only
  2. 2 only
  3. 1 and 3
  4. 2 and 3
Show answer and explanation

Answer: C. 1 and 3

C and Br increase oxidation state → oxidation.

Practise all 19 Redox questions

Sessions with Redox questions

SessionPaper 1Paper 2
May/June 20252–
May/June 20242–
Oct/Nov 20242–
May/June 20232–
Oct/Nov 20232–
May/June 20222–
Oct/Nov 20222–
May/June 20212–
Oct/Nov 202121

Common questions

What does the Redox topic cover on this page?

19 real O Level Chemistry (5070) questions on Redox from 2021 to 2025, from Paper 1, Paper 2. Each one shows the year, session and paper it came from.

Do I get the answers and explanations?

Yes. Every question shows the correct answer and a short explanation the moment you answer.

Is it free?

You can start free with no signup. A small set of papers per subject is free, and Premium unlocks every paper, the full question bank and the paper PDFs.

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