Redox: past paper questions
Real questions on redox
The newest 20 of 140 written questions. Open one to see it on the real paper.
- 5070/21 · October/November 2025 · Q3a(i)[2]
Identify the energy changes labelled A and B. energy change A
See it on the paper → - 5070/21 · October/November 2025 · Q5d(ii)[1]
Predict if nickel reacts with aqueous copper( II ) ions. Explain your answer. prediction explanation
See it on the paper → - 5070/22 · October/November 2025 · Q6c[2]
When aqueous hydrogen peroxide reacts with acidified aqueous potassium manganate( VII ) there is a colour change from purple to colourless. When aqueous hydrogen peroxide reacts with aqueous potassium iodide there is a colour change from colourless to brown. Explain what these observations indicate about the chemical p...
See it on the paper → - 5070/21 · May/June 2025 · Q1c[1]
reacts with warm aqueous sodium hydroxide and aluminium foil to give a gas that turns damp red litmus paper blue
See it on the paper → - 5070/21 · May/June 2025 · Q1d[1]
has an aqueous solution that is used to test for an oxidising agent
See it on the paper → - 5070/21 · May/June 2025 · Q1e[1]
has an aqueous solution that reacts with copper metal.
See it on the paper → - 5070/21 · May/June 2025 · Q5b(i)[2]
Explain how carbon monoxide, CO, is formed in a petrol engine. Include a symbol equation.
See it on the paper → - 5070/21 · May/June 2025 · Q5b(ii)[2]
Explain how nitrogen monoxide, NO, is formed in a petrol engine. Include a symbol equation.
See it on the paper → - 5070/21 · May/June 2025 · Q5c(i)[2]
Explain why this reaction involves both oxidation and reduction.
See it on the paper → - 5070/21 · May/June 2025 · Q6c(ii)[1]
During the reaction chlorine is reduced. Explain why, using ideas about electrons.
See it on the paper → - 5070/22 · May/June 2025 · Q6c(ii)[1]
During the reaction bromine is reduced. Explain why, using ideas about electrons.
See it on the paper → - 5070/21 · October/November 2024 · Q2a(i)[1]
This reaction is a redox reaction. State the meaning of the term redox reaction.
See it on the paper → - 5070/21 · October/November 2024 · Q2a(ii)[1]
Explain how carbon monoxide acts as a reducing agent in this reaction.
See it on the paper → - 5070/21 · October/November 2024 · Q2c[2]
Describe how slag is formed in the blast furnace. Include a symbol equation in your answer.
See it on the paper → - 5070/21 · October/November 2024 · Q2f[2]
Iron reacts with hot concentrated sulfuric acid. The products are iron( III ) sulfate, sulfur dioxide and a liquid that turns anhydrous copper( II ) sulfate blue. Construct the symbol equation for this reaction.
See it on the paper → - 5070/22 · October/November 2024 · Q2f[2]
Fe 3 O 4 reacts with concentrated hydrochloric acid. The products are iron( II ) chloride, iron( III ) chloride and a liquid that turns blue cobalt( II ) chloride paper pink. Construct the symbol equation for this reaction.
See it on the paper → - 5070/22 · October/November 2024 · Q6d(i)[1]
The oxidation number of hydrogen in NH 3 is +1. Deduce the oxidation number of nitrogen in NH 3 .
See it on the paper → - 5070/22 · October/November 2024 · Q6d(ii)[1]
Explain why this is not a redox reaction by referring to the oxidation number of nitrogen.
See it on the paper → - 5070/22 · October/November 2024 · Q7e(i)[3]
Name the three products of this reaction.
See it on the paper → - 5070/21 · May/June 2024 · Q2d(i)[2]
Explain, using ideas about bond breaking and bond making, why this reaction is exothermic.
See it on the paper →
What examiners said
The catalyst was quite well known. Common incorrect responses included vanadium(II) oxide, vanadium oxide, phosphoric acid and iron. A small number omitted the question.
— Examiner report, October/November 2023, 5070/21 Q2(f)(ii) (Cambridge)
Candidates found this very challenging. Many confused oxidising agent and oxidation and so thought calcium gained electrons or thought zinc gained the electrons rather than zinc ions.
— Examiner report, October/November 2023, 5070/21 Q4(d)(i) (Cambridge)
Candidates did not always use the correct particle in their answers, for example ‘iodine loses electrons’ rather than iodide loses electrons. Some candidates referred to hydrogen ions gaining electrons rather than the manganese in MnO2 gaining electrons. Other candidates gave answers that referred to electron gain rather than electron loss.
— Examiner report, October/November 2023, 5070/22 Q4(d)(i) (Cambridge)
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