Chemical reactions: 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 15Oct/Nov 2025, paper 11Multiple choice1 markHas a diagram

  The rate of reaction between calcium carbonate and dilute hydrochloric acid is measured in three separate experiments. In experiment 1, the calcium carbonate is powdered, and an excess of hydrochloric acid is used.

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• Question 14Oct/Nov 2024, paper 11Multiple choice1 markHas a diagram

  Two gases react together to produce a single product. The rate of the reaction is affected by an increase in pressure. The reaction is catalysed by platinum.

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• Question 16Oct/Nov 2025, paper 11Multiple choice1 mark

  The equation shows the reversible reaction between nitrogen and hydrogen to form ammonia. $${\mathrm{N}}_2+3{\mathrm{H}}_2\rightleftharpoons 2{\mathrm{N}\mathrm{H}}_3$$ The forward reaction is exothermic. Which statement is correct when the temperature is increased?

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• Question 15Oct/Nov 2024, paper 11Multiple choice1 markHas a diagram

  Calcium carbonate reacts with excess dilute hydrochloric acid to form carbon dioxide. The reaction is investigated in two experiments. The rate of the reactions is compared by measuring the volume of carbon dioxide formed over time in each experiment.

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• Question 16May/June 2026, paper 11Multiple choice1 mark

  When bismuth(III) chloride, ${\text{BiCl}}_3$, is added to water, a reaction occurs and a white precipitate of $\text{BiOCl}$ is formed.

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• Question 14Oct/Nov 2025, paper 12Multiple choice1 markHas a diagram

  Two changes are described. change 1 Copper is added to concentrated nitric acid. Nitrogen dioxide is produced.

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• Question 16Oct/Nov 2024, paper 11Multiple choice1 mark

  If calcium carbonate is heated in a closed container, it will decompose, forming calcium oxide and carbon dioxide. Calcium oxide and carbon dioxide can recombine to form calcium carbonate.

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• Question 18Oct/Nov 2023, paper 11Multiple choice1 markHas a diagram

  Aqueous bromine is an equilibrium mixture. $$\mathrm{B}{\mathrm{r}}_2(\mathrm{a}\mathrm{q})+{\mathrm{H}}_2\mathrm{O}(\mathrm{l})\rightleftharpoons \mathrm{O}\mathrm{B}{\mathrm{r}}^{-}(\mathrm{a}\mathrm{q})+\mathrm{B}{\mathrm{r}}^{-}(\mathrm{a}\mathrm{q})+2{\mathrm{H}}^{+}(\mathrm{a}\mathrm{q})$$ Aqueous bromine is orange in colour. The species on the right-hand side of the equation are colourless.

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• Question 17May/June 2026, paper 11Multiple choice1 mark

  The Haber process is used to make ammonia. Which catalyst is used in the Haber process?

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• Question 15Oct/Nov 2025, paper 12Multiple choice1 mark

  Which change increases the rate of a chemical reaction?

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• Question 17Oct/Nov 2024, paper 11Multiple choice1 markHas a diagram

  Which set of conditions is used in the Contact process?

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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 13May/June 2026, paper 12Multiple choice1 mark

  Which property of a substance always remains the same during a physical change?

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• Question 16Oct/Nov 2025, paper 12Multiple choice1 markHas a diagram

  In two separate experiments, 1 and 2, an excess of powdered calcium carbonate reacts in a flask with dilute hydrochloric acid. In experiment 1, the volume of carbon dioxide evolved is measured at regular time intervals.

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

  Some metals and the compounds in their ores are shown.

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• Question 14May/June 2026, paper 12Multiple choice1 markHas a diagram

  The reaction pathway diagram for both the catalysed and uncatalysed reactions between ${\text{N}}_2$ and ${\text{H}}_2$ in the Haber process is shown. What is the activation energy for the formation of ${\text{NH}}_3$ in the presence of a catalyst?

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• Question 17Oct/Nov 2025, paper 12Multiple choice1 mark

  Which statements about the Haber process for the manufacture of ammonia are correct?

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• Question 22Oct/Nov 2024, paper 11Multiple choice1 markHas a diagram

  When heated, copper(II) sulfate crystals, ${\text{CuSO}}_4\cdot 5{\text{H}}_2\text{O}$, react as shown. $${\text{CuSO}}_4\cdot 5{\text{H}}_2\text{O}(\text{s})\to {\text{CuSO}}_4(\text{s})+5{\text{H}}_2\text{O}(\text{g})$$ When ......1...... copper(II) sulfate, which is ......2......

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• Question 15Oct/Nov 2023, paper 12Multiple choice1 mark

  Physical changes and chemical changes can occur in substances. Which process describes a chemical change?

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• Question 15May/June 2026, paper 12Multiple choice1 mark

  Elements X and Y react together in a reversible reaction to form ${\text{XY}}_2$. $$\text{X}+2\text{Y}\rightleftharpoons {\text{XY}}_2$$ $1.0\text{ mol}$ of X is mixed with $1.0\text{ mol}$ of Y and the mixture is left to react until an equilibrium position is reached.

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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 16Oct/Nov 2024, paper 12Multiple choice1 mark

  Which statement about a physical change is correct?

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• Question 16Oct/Nov 2023, paper 12Multiple choice1 markHas a diagram

  Two methods used by students to measure the rate of a reaction are the 'disappearing cross' method and the 'loss of mass' method. ● For the 'disappearing cross' method, the student measures the time taken for the reaction mixture to go cloudy.

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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 7Oct/Nov 2025, paper 21Structured13 marksHas a diagram

  Ethene is used to make ethanol and poly(ethene). Fig. 7.1 shows the displayed formula of ethene. Alkenes such as ethene are manufactured from hydrocarbons such as ${\mathrm{C}}_{12}{\mathrm{H}}_{26}$.

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• Question 17Oct/Nov 2024, paper 12Multiple choice1 markHas a diagram

  Gas P decomposes to form gas Q. $$x\text{P}\to y\text{Q}$$ Two experiments are done to investigate the rate of reaction. The conditions are the same except that two different temperatures, $T_1$ and $T_2$, are used.

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• Question 17Oct/Nov 2023, paper 12Multiple choice1 markHas a diagram

  Hydrogen is used as a reactant both in the Haber process and in its addition to alkenes. Which row is correct?

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

  Choose from the following compounds to answer the questions.

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