Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
Redox — exam questions
12 original Incandio exam-style questions on redox, 26 marks, about 26 minutes of writing. Each one carries the command word, the tariff and the specification statement it assesses, exactly as a paper presents them. This is an original Incandio practice question, written to reflect the structure and demands of the qualification. It is not an official Pearson Edexcel past-paper question.
This is the practice set for Redox — the lesson that teaches it. Read the lesson first if the idea is new; come here when you want to find out whether you can turn it into marks. Completely free, no account needed to read.
What these questions ask of you
8 command words run through this set, and on Pearson Edexcel International GCSE Chemistry each one means something precise. Answering the wrong command is the commonest way a candidate who understands the lesson still loses the mark.
- Which (1 mark)
- one option chosen from the set given
- State what is meant by (1–2 marks)
- the definition
- Give (1–2 marks)
- a short factual answer — the most common chemistry command
- Describe (2–5 marks)
- developed, linked statements of what happens or what is observed Misread as: giving one bare observation where the tariff asked for a developed account
- Explain (2–4 marks)
- the reason, in terms of particles, bonding, energy or equilibrium Misread as: describing the observation without giving the chemistry that causes it
- Suggest (1–3 marks)
- a plausible answer applying taught chemistry to an unfamiliar substance
- Identify (1–2 marks)
- the correct substance or feature selected from what is given
- Give a reason (1–2 marks)
- one reason — in chemistry this is a one-mark command
Assessed on Paper 1 (4CH1/1C) and Paper 2 (4CH1/2C), against AO1, AO2, AO3.
Where these sit in the specification
Pearson Edexcel International GCSE Chemistry (4CH1) — statements 2.20 · 2.21. Incandio is aligned to this specification; it is not published by, endorsed by or affiliated with Pearson, and it reproduces none of Pearson's wording.
The 12 questions
Answer them on paper, then open the lesson's exam practice to have them marked. The mark scheme, the accepted and rejected answers and the annotated model answer are in Incandio and are not printed here — an answer beside its question is not practice.
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Table 1 — three reactions Equation reaction 1 2Mg + O₂ → 2MgO reaction 2 CuO + H₂ → Cu + H₂O reaction 3 Zn + CuSO₄ → ZnSO₄ + Cu (a)
(1)Identify
Identify the substance that is reduced in reaction 2 of Table 1.
Table 1 — three reactions Equation reaction 1 2Mg + O₂ → 2MgO reaction 2 CuO + H₂ → Cu + H₂O reaction 3 Zn + CuSO₄ → ZnSO₄ + Cu (b)
(2)Give a reason
Give the reason for that answer, and name the reducing agent in reaction 2.
Table 1 — three reactions Equation reaction 1 2Mg + O₂ → 2MgO reaction 2 CuO + H₂ → Cu + H₂O reaction 3 Zn + CuSO₄ → ZnSO₄ + Cu (c)
(3)Explain
Explain, in terms of electrons, why reaction 3 in Table 1 is a redox reaction.
Table 1 — three reactions Equation reaction 1 2Mg + O₂ → 2MgO reaction 2 CuO + H₂ → Cu + H₂O reaction 3 Zn + CuSO₄ → ZnSO₄ + Cu (d)
(3)Suggest
Reaction 1 in Table 1 can be described as redox using either definition, but reaction 3 can only be described that way using one of them. Suggest why.
Table 1 — three reactions Equation reaction 1 2Mg + O₂ → 2MgO reaction 2 CuO + H₂ → Cu + H₂O reaction 3 Zn + CuSO₄ → ZnSO₄ + Cu (Total for Question 1 = 9 marks)
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(1)Which
Which describes oxidation in terms of electrons?
Description A gain of electrons B loss of electrons C loss of protons D gain of neutrons (Total for Question 2 = 1 mark)
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(1)State what is meant by
State what is meant by reduction in terms of oxygen.
(Total for Question 3 = 1 mark)
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(1)Give
Give the name for a reaction in which oxidation and reduction happen at the same time.
(Total for Question 4 = 1 mark)
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(2)Describe
Describe what an oxidising agent does in a reaction, and what happens to it.
(Total for Question 5 = 2 marks)
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(3)Explain
Explain why oxidation can never happen on its own in a chemical reaction.
(Total for Question 6 = 3 marks)
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(2)Explain
Explain, in terms of electrons, what happens to the magnesium when it reacts with dilute hydrochloric acid.
(Total for Question 7 = 2 marks)
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(3)Suggest
A student investigating reactions between dilute acids and metals wants a fair comparison. Suggest three things she should keep the same.
(Total for Question 8 = 3 marks)
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(4)Explain
In the reaction between zinc and copper(II) ions, explain which species is oxidised, which is reduced, and why the two must happen together.
(Total for Question 9 = 4 marks)
Have them marked, then defend the answer
Practice tells you the mark; teaching it back tells you whether you understand it. On Incandio a topic counts as mastered only once you have taught it and defended it.
- Mark these questions — 12 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain redox to Ember, an AI pupil who does not have it yet and asks the awkward question.
- Defend it — argue it against Antoine Lavoisier over three rounds, marked against descriptors you can read first.
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Back to the lesson
- Redox — The same reaction described twice — once by what gains oxygen, and once by what loses electrons.
- All of Incandio Chemistry · Incandio Exam Practice