The mole and the Avogadro constant: past paper questions

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• Question 9May/June 2026, paper 11Multiple choice1 mark

  Hydrated magnesium sulfate has the formula ${\text{MgSO}}_4\cdot 7{\text{H}}_2\text{O}$.

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• Question 10Oct/Nov 2025, paper 11Multiple choice1 mark

  How many atoms are there in $27.0\mathrm{g}$ of water, ${\mathrm{H}}_2\mathrm{O}$?

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• Question 9Oct/Nov 2024, paper 11Multiple choice1 mark

  Which mass of carbon contains the same number of atoms as $16.0\text{ g}$ of sulfur?

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• Question 8Oct/Nov 2023, paper 11Multiple choice1 mark

  Compound Y is the only substance formed when $500{\mathrm{c}\mathrm{m}}^3$ of ammonia reacts with $250{\mathrm{c}\mathrm{m}}^3$ of carbon dioxide. All measurements are at r.t.p. What is the formula of Y?

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• Question 10Oct/Nov 2024, paper 11Multiple choice1 mark

  Compound X contains carbon, hydrogen and oxygen only. It has an $M_r$ of 90. $100\text{ g}$ of compound X contains $40.0\text{ g}$ of carbon and $6.7\text{ g}$ of hydrogen.

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• Question 9Oct/Nov 2023, paper 11Multiple choice1 mark

  How many sodium ions are there in $30\mathrm{g}$ of sodium sulfate?

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• Question 9Oct/Nov 2025, paper 12Multiple choice1 markHas a diagram

  A mixture of $2\text{ g}$ of hydrogen and $32\text{ g}$ of oxygen occupies a volume, $V$, measured at r.t.p. The gases react until there is no further change.

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• Question 29Oct/Nov 2024, paper 11Multiple choice1 markHas a diagram

  Sodium phosphate, ${\text{Na}}_3{\text{PO}}_4$, and ammonium nitrate, ${\text{NH}}_4{\text{NO}}_3$, are both used as fertilisers. Which row shows the correct percentage by mass of the element in each compound that improves plant growth?

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

  The complete combustion of $20{\mathrm{c}\mathrm{m}}^3$ of a gaseous alkane, X, requires $130{\mathrm{c}\mathrm{m}}^3$ of oxygen.

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• Question 8May/June 2026, paper 12Multiple choice1 mark

  Nitrogen monoxide and oxygen react to form nitrogen dioxide.

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• Question 34Oct/Nov 2024, paper 11Multiple choice1 mark

  How many moles of oxygen are required for the complete combustion of 2 moles of ethanol?

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• Question 9Oct/Nov 2023, paper 12Multiple choice1 mark

  Which reaction would produce the greatest volume of carbon dioxide at room temperature and pressure?

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• Question 9May/June 2026, paper 12Multiple choice1 mark

  During a titration, $25.0{\text{ cm}}^3$ of $0.050\text{ mol}\mathrm{/}{\text{dm}}^3$ aqueous sodium hydroxide, $\text{NaOH}$, reacts exactly with $20.0{\text{ cm}}^3$ of dilute phosphoric acid, ${\text{H}}_3{\text{PO}}_4$.

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• Question 3Oct/Nov 2025, paper 21Structured7 marksHas a diagram

  Sodium hydrogencarbonate decomposes when heated.

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• Question 9Oct/Nov 2024, paper 12Multiple choice1 mark

  Which contains the greatest mass of oxygen?

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• Question 11Oct/Nov 2023, paper 12Multiple choice1 mark

  The equation shows the production of iron by the reduction of iron(III) oxide. $${\text{Fe}}_2{\text{O}}_3+3\text{CO}\to 2\text{Fe}+3{\text{CO}}_2$$ 80 tonnes of iron(III) oxide produces 50 tonnes of iron. What is the percentage yield?

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• Question 34May/June 2026, paper 12Multiple choice1 mark

  X mol of ethanol and X mol of propan-1-ol separately undergo complete combustion at the same temperature and pressure.

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• Question 6Oct/Nov 2025, paper 21Structured9 marksHas a diagram

  This question is about an unsaturated hydrocarbon called ethyne. Fig. 6.1 shows the displayed formula of ethyne. $$\mathrm{H}-\mathrm{C}\equiv \mathrm{C}-\mathrm{H}$$ Fig. 6.1 Draw a dot-and-cross diagram to show the electronic arrangement in a molecule of ethyne.

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• Question 31Oct/Nov 2024, paper 12Multiple choice1 mark

  Iron can be extracted from the ore hematite. What is the maximum mass of iron that is produced from $500\text{ kg}$ of hematite?

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• Question 7Oct/Nov 2023, paper 21Structured11 marks

  Dilute ethanoic acid reacts with aqueous calcium hydroxide.

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• Question 2May/June 2026, paper 21Structured12 marks

  Sodium azide, ${\mathrm{N}\mathrm{a}\mathrm{N}}_3$, decomposes when heated to make sodium and nitrogen. $$2{\mathrm{N}\mathrm{a}\mathrm{N}}_3(\mathrm{s})\to 2\mathrm{N}\mathrm{a}(\mathrm{s})+3{\mathrm{N}}_2(\mathrm{g})$$ A sample of $13.6\mathrm{g}$ of sodium azide is fully decomposed.

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• Question 3Oct/Nov 2025, paper 22Structured7 marksHas a diagram

  The equation for the reaction between aluminium and dilute hydrochloric acid is shown. $$2\mathrm{A}\mathrm{l}(\mathrm{s})+6\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q})\to 2{\mathrm{A}\mathrm{l}\mathrm{C}\mathrm{l}}_3(\mathrm{a}\mathrm{q})+3{\mathrm{H}}_2(\mathrm{g})$$ Fig. 3.1 shows the reaction pathway diagram for this reaction.

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• Question 38Oct/Nov 2024, paper 12Multiple choice1 mark

  In a titration, a $25.0{\text{ cm}}^3$ sample of $0.100{\text{ mol / dm}}^3$ sodium hydroxide is exactly neutralised by $16.2{\text{ cm}}^3$ of dilute sulfuric acid. The equation for the reaction is shown.

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• Question 9Oct/Nov 2023, paper 21Structured9 marks

  Table 9.1 shows the melting points and relative electrical conductivities of three elements.

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• Question 5May/June 2026, paper 21Structured14 marks

  Aluminium sulfate is prepared by reacting excess aluminium with hot dilute sulfuric acid.

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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 5Oct/Nov 2024, paper 21Structured14 marksHas a diagram

  A student adds large pieces of copper(II) carbonate to dilute hydrochloric acid. The copper(II) carbonate is in excess. Complete the equation by adding state symbols for the products.

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• Question 7Oct/Nov 2023, paper 22Structured11 marks

  Dilute hydrochloric acid reacts with aqueous sodium carbonate.

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• Question 2May/June 2026, paper 22Structured11 marks

  Potassium superoxide, ${\mathrm{K}\mathrm{O}}_2$, reacts with carbon dioxide to make potassium carbonate and oxygen.

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• Question 12May/June 2025, paper 11Multiple choice1 mark

  $10{\text{ cm}}^3$ of hydrogen gas is mixed with $x{\text{ cm}}^3$ of chlorine gas. The equation for the reaction that takes place is shown. $${\mathrm{H}}_2(\mathrm{g})+\mathrm{C}{\mathrm{l}}_2(\mathrm{g})\to 2\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{g})$$ All the hydrogen reacts.

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