Redox: past paper questions

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• Question 12May/June 2026, paper 11Multiple choice1 mark

  Molten sodium chloride is electrolysed. Which change occurs at the cathode?

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• Question 18Oct/Nov 2025, paper 12Multiple choice1 markHas a diagram

  Acidified aqueous potassium manganate(VII) is used as a test reagent. When it is added to an aqueous solution of compound M, the colour of the test reagent changes from ......1...... .

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• Question 18Oct/Nov 2024, paper 11Multiple choice1 markHas a diagram

  Copper forms a red oxide, ${\text{Cu}}_2\text{O}$, and a black oxide, $\text{CuO}$. In the presence of a catalyst, aqueous hydrogen peroxide, ${\text{H}}_2{\text{O}}_2$, decomposes to form water. The black oxide has copper in a ......1......

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• Question 19Oct/Nov 2023, paper 11Multiple choice1 mark

  In which substance does the nitrogen atom have the same oxidation number as the nitrogen atom in $\mathrm{H}\mathrm{N}{\mathrm{O}}_2$?

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• Question 16May/June 2026, paper 12Multiple choice1 markHas a diagram

  Iodine, ${\text{I}}_2$, reacts with thiosulfate ions, ${\text{S}}_2{\text{O}}_3^{2-}$. $${\text{I}}_2(\text{aq})+2{\text{S}}_2{\text{O}}_3^{2-}(\text{aq})\to 2{\text{I}}^{-}(\text{aq})+{\text{S}}_4{\text{O}}_6^{2-}(\text{aq})$$ Which row is correct?

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• Question 6Oct/Nov 2025, paper 22Structured11 marksHas a diagram

  This question is about the covalent compound hydrogen peroxide. Fig. 6.1 shows the displayed formula of hydrogen peroxide. $$\mathrm{H}-\mathrm{O}-\mathrm{O}-\mathrm{H}$$ Fig. 6.1 Draw the dot-and-cross diagram to show the electronic arrangement in a molecule of hydrogen peroxide.

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• Question 20Oct/Nov 2024, paper 12Multiple choice1 markHas a diagram

  Peroxodisulfate ions, ${\text{S}}_2{\text{O}}_8^{2-}$, react with iron(II) ions, ${\text{Fe}}^{2+}$.

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• Question 29Oct/Nov 2023, paper 11Multiple choice1 markHas a diagram

  Some metals and the compounds in their ores are shown.

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• Question 1May/June 2026, paper 21Structured5 marks

  Choose from the following compounds to answer the questions.

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• Question 5May/June 2025, paper 21Structured12 marks

  Vehicles that use petrol as a fuel produce several air pollutants. Petrol is a mixture of hydrocarbons which includes octane, ${\mathrm{C}}_8{\mathrm{H}}_{18}$. Explain why octane is a hydrocarbon.

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• Question 6Oct/Nov 2024, paper 22Structured9 marksHas a diagram

  Fig. 6.1 shows the structures of boron nitride and hydrazine. Boron nitride has a structure similar to diamond. Explain why boron nitride has a high melting point.

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• Question 18Oct/Nov 2023, paper 12Multiple choice1 mark

  Chlorine, ${\text{Cl}}_2$, reacts with iron(II), ${\text{Fe}}^{2+}$, ions. $${\text{Cl}}_2+2{\text{Fe}}^{2+}\to 2{\text{Cl}}^{-}+2{\text{Fe}}^{3+}$$ Which statement about this reaction is correct?

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• Question 4May/June 2026, paper 21Structured11 marks

  Potassium iodide is an ionic compound. Concentrated and dilute aqueous potassium iodide are separately electrolysed using graphite electrodes. Complete Table 4.1 about the products of the two electrolysis reactions.

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• Question 6May/June 2025, paper 21Structured16 marks

  Chlorine, ${\mathrm{C}\mathrm{l}}_2$, is in Group VII of the Periodic Table. The melting point of chlorine is $-101{}^{\circ }\mathrm{C}$ and the boiling point is $-35{}^{\circ }\mathrm{C}$. Explain why chlorine is a liquid at $-50{}^{\circ }\mathrm{C}$.

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• Question 21May/June 2024, paper 11Multiple choice1 mark

  Many reactions involve oxidation and reduction. Which statement is correct?

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• Question 4Oct/Nov 2023, paper 21Structured10 marksHas a diagram

  Concentrated aqueous calcium bromide is electrolysed using graphite electrodes. Predict the product at each electrode.

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• Question 1May/June 2026, paper 22Structured5 marks

  Choose from the following compounds to answer the questions.

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• Question 22May/June 2024, paper 11Multiple choice1 mark

  The equation for a reaction is shown. $$\mathrm{C}{\mathrm{l}}_2+2\mathrm{K}\mathrm{B}\mathrm{r}\to 2\mathrm{K}\mathrm{C}\mathrm{l}+\mathrm{B}{\mathrm{r}}_2$$ Which statement about this reaction is correct?

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• Question 4Oct/Nov 2023, paper 22Structured10 marksHas a diagram

  Concentrated aqueous magnesium iodide is electrolysed using graphite electrodes. Predict the product at each electrode.

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• Question 4May/June 2026, paper 22Structured11 marks

  Copper(II) sulfate is an ionic compound. The electrolysis of aqueous copper(II) sulfate is done using copper or graphite electrodes. Complete Table 4.1 about the observations made in the two electrolysis reactions.

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• Question 20May/June 2024, paper 12Multiple choice1 mark

  Chlorine reacts with aqueous sodium bromide to form aqueous sodium chloride and bromine. Which statement about this reaction is correct?

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• Question 17May/June 2023, paper 11Multiple choice1 mark

  The combustion of methane is a redox reaction. $${\text{CH}}_4+2{\text{O}}_2\to {\text{CO}}_2+2{\text{H}}_2\text{O}$$ Which statement about this reaction is correct?

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• Question 4May/June 2024, paper 21Structured9 marks

  Potassium iodide, $\mathrm{K}\mathrm{I}$, is an ionic solid composed of a lattice of potassium ions and iodide ions. Explain why potassium iodide has a high melting point.

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• Question 18May/June 2023, paper 11Multiple choice1 mark

  Which method of preparation of magnesium sulfate is an example of a redox reaction?

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• Question 4May/June 2024, paper 22Structured9 marks

  Calcium bromide, ${\mathrm{C}\mathrm{a}\mathrm{B}\mathrm{r}}_2$, is an ionic solid composed of a lattice of calcium ions and bromide ions. Explain why calcium bromide has a high melting point.

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• Question 19May/June 2023, paper 12Multiple choice1 mark

  Iron(II) ions react with chlorine. $$2{\mathrm{F}\mathrm{e}}^{2+}(\mathrm{a}\mathrm{q})+{\mathrm{C}\mathrm{l}}_2(\mathrm{g})\to 2{\mathrm{F}\mathrm{e}}^{3+}(\mathrm{a}\mathrm{q})+2{\mathrm{C}\mathrm{l}}^{-}(\mathrm{a}\mathrm{q})$$ Which statement about this reaction is correct?

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• Question 20May/June 2023, paper 12Multiple choice1 markHas a diagram

  Which reagent and observation describes the test for a reducing agent?

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• Question 31May/June 2023, paper 12Multiple choice1 mark

  Pieces of magnesium can be attached to the steel hull of a ship to prevent rusting. This is sacrificial protection. Which statements about sacrificial protection are correct?

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• Question 2May/June 2023, paper 21Structured8 marks

  Group I includes the elements lithium, sodium and potassium. State two physical properties of lithium.

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• Question 1May/June 2023, paper 22Structured6 marks

  Choose from the following oxides to answer the questions. CO ${\mathrm{C}\mathrm{O}}_2$ CaO CuO ${\mathrm{F}\mathrm{e}}_2{\mathrm{O}}_3$ ${\mathrm{H}}_2\mathrm{O}$ ${\mathrm{S}\mathrm{O}}_2$ ${\mathrm{S}\mathrm{i}\mathrm{O}}_2$ ZnO Each oxide may be used once, more than once or not at all. State which oxide: is neutral

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