The mole and the Avogadro constant: past paper questions

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• Question 8May/June 2026, paper 12Multiple choice1 markHas a diagram

  The equation for the complete combustion of methane, ${\mathrm{C}\mathrm{H}}_4$, is shown.

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• Question 9Oct/Nov 2025, paper 11Multiple choice1 mark

  The equation for the combustion of magnesium is shown. $$2\text{Mg}+{\text{O}}_2\to 2\text{MgO}$$ Which mass of magnesium oxide will be formed from the complete reaction of $9.6\text{g}$ of magnesium?

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

  The equation for the production of ammonia, ${\text{NH}}_3$, is shown. $${\text{N}}_2(\text{g})+3{\text{H}}_2(\text{g})\to 2{\text{NH}}_3(\text{g})$$ Which mass of nitrogen is required to make 51 tonnes of ammonia?

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

  The equation for the combustion of methane is shown. $${\text{CH}}_4+2{\text{O}}_2\to {\text{CO}}_2+2{\text{H}}_2\text{O}$$ Which mass of methane produces $36\text{ g}$ of water?

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

  Four units are listed. 1 ${\mathrm{d}\mathrm{m}}^3\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ 2 $\mathrm{g}\mathrm{/}{\mathrm{d}\mathrm{m}}^3$ 3 $\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{/}{\mathrm{d}\mathrm{m}}^3$ 4 $\mathrm{g}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ Which units are units of concentration?

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• Question 17Oct/Nov 2025, paper 11Multiple choice1 mark

  What are the units of concentration?

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• Question 8Oct/Nov 2024, paper 13Multiple choice1 mark

  Magnesium burns in oxygen to form magnesium oxide. The equation for the reaction is shown. $$2\text{Mg}+{\text{O}}_2\to 2\text{MgO}$$ Which mass of magnesium oxide is formed when $48\text{ g}$ of magnesium is burned?

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• Question 10Oct/Nov 2023, paper 12Multiple choice1 mark

  Limestone is used to reduce sulfur dioxide emissions from coal-fired power stations. The equation for the reaction is shown.

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• Question 9May/June 2026, paper 21Multiple choice1 mark

  Magnesium reacts with steam to form hydrogen. $$\text{Mg}+{\text{H}}_2\text{O}\to \text{MgO}+{\text{H}}_2$$ How many molecules of hydrogen gas are made when $3.6\text{ g}$ of magnesium are heated with $1.8\text{ g}$ of steam?

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• Question 8Oct/Nov 2025, paper 21Multiple choice1 mark

  The equation for the reaction between dilute ethanoic acid and aqueous lithium hydroxide is shown.

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• Question 10Oct/Nov 2024, paper 21Multiple choice1 mark

  Calcium carbonate is heated. Calcium oxide and carbon dioxide gas are formed. The equation for the reaction is shown.

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• Question 10Oct/Nov 2023, paper 23Multiple choice1 mark

  $1.0\text{ mol}$ of silver nitrate, ${\text{AgNO}}_3$, contains $1.2\times {10}^{24}$ ions. How many ions are there in $0.25\text{ mol}$ of iron(III) oxide, ${\text{Fe}}_2{\text{O}}_3$?

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• Question 10May/June 2026, paper 22Multiple choice1 mark

  The equation for the reaction between magnesium and dilute hydrochloric acid is shown. $$\text{Mg(s)}+2\text{HCl(aq)}\to {\text{MgCl}}_2\text{(aq)}+{\text{H}}_2\text{(g)}$$ $0.10\text{ mol Mg}$ is added to $100{\text{ cm}}^3$ of $1.0\text{ mol}\mathrm{/}{\text{dm}}^3\text{ HCl(aq)}$.

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• Question 10Oct/Nov 2025, paper 21Multiple choice1 mark

  The equation for the reaction between copper(II) oxide, $\mathrm{C}\mathrm{u}\mathrm{O}$, and ammonia is given.

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• Question 10Oct/Nov 2024, paper 22Multiple choice1 mark

  The equation for the decomposition of ammonium carbonate, $({\mathrm{N}\mathrm{H}}_4{)}_2{\mathrm{C}\mathrm{O}}_3$, is shown.

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• Question 4Oct/Nov 2023, paper 41Structured12 marksHas a diagram

  Aqueous hydrogen peroxide, ${\mathrm{H}}_2{\mathrm{O}}_2$, slowly forms water and oxygen at room temperature and pressure, r.t.p. This reaction is catalysed by manganese(IV) oxide. The equation is shown.

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• Question 12May/June 2026, paper 23Multiple choice1 mark

  The equation for the reaction of dilute sulfuric acid and aqueous sodium hydroxide is shown. $${\text{H}}_2{\text{SO}}_4+2\text{NaOH}\to {\text{Na}}_2{\text{SO}}_4+2{\text{H}}_2\text{O}$$ $25.0{\text{ cm}}^3$ of aqueous sodium hydroxide is measured into a conical flask.

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• Question 11Oct/Nov 2025, paper 21Multiple choice1 mark

  How many atoms are present in $1.00\mathrm{m}\mathrm{o}\mathrm{l}$ of argon?

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• Question 11Oct/Nov 2024, paper 22Multiple choice1 mark

  What is the empirical formula of a compound that contains $3.66\mathrm{g}$ of hydrogen, $37.8\mathrm{g}$ of phosphorus and $58.5\mathrm{g}$ of oxygen?

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• Question 4Oct/Nov 2023, paper 43Structured15 marks

  This question is about sulfuric acid and salts that are made from sulfuric acid. Zinc reacts with dilute sulfuric acid. Aqueous zinc sulfate is one of the products.

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• Question 13May/June 2026, paper 23Multiple choice1 mark

  What is the total number of atoms in $0.0100\text{ mol}$ of methane, ${\text{CH}}_4$?

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• Question 10Oct/Nov 2025, paper 22Multiple choice1 mark

  The equation for the combustion of ethanol is shown. $${\text{C}}_2{\text{H}}_5\text{OH}+3{\text{O}}_2\to 2{\text{CO}}_2+3{\text{H}}_2\text{O}$$ The relative molecular mass, $M_r$, of ethanol is 46. Which statement about the reaction is correct?

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• Question 9Oct/Nov 2024, paper 23Multiple choice1 markHas a diagram

  The structure of ethene is shown. How many hydrogen atoms and how many carbon atoms are in one mole of ethene?

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• Question 8May/June 2023, paper 21Multiple choice1 mark

  Heating iron sulfide, ${\mathrm{F}\mathrm{e}\mathrm{S}}_2$, in air produces sulfur dioxide. $$4{\mathrm{F}\mathrm{e}\mathrm{S}}_2+11{\mathrm{O}}_2\to 2{\mathrm{F}\mathrm{e}}_2{\mathrm{O}}_3+8{\mathrm{S}\mathrm{O}}_2$$ What is the maximum mass of sulfur dioxide produced from $120\text{ kg}$ of iron sulfide?

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• Question 6May/June 2026, paper 41Structured16 marks

  This question is about metallic compounds. Zinc oxide, $\text{ZnO}$, reacts with both acids and alkalis to produce salts. State the term given to oxides that react with both acids and alkalis.

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• Question 11Oct/Nov 2025, paper 22Multiple choice1 markHas a diagram

  A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen only. The relative molecular mass, $M_r$, of the compound is 60. Which row shows the empirical formula and the molecular formula of the compound?

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• Question 7May/June 2023, paper 22Multiple choice1 mark

  Which sample contains the largest number of molecules?

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• Question 4May/June 2026, paper 43Structured12 marksHas a diagram

  Aqueous hydrogen peroxide, ${\mathrm{H}}_2{\mathrm{O}}_2$, decomposes to produce water and oxygen gas. The reaction is catalysed by manganese(IV) oxide. A student adds powdered manganese(IV) oxide to aqueous hydrogen peroxide in a conical flask as shown in Figure 4.1.

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• Question 12Oct/Nov 2025, paper 23Multiple choice1 mark

  Calcium carbonate decomposes when heated strongly. $${\text{CaCO}}_3(\text{s})\to \text{CaO}(\text{s})+{\text{CO}}_2(\text{g})$$ How many gaseous molecules are produced when $10.0\text{ g}$ of calcium carbonate is completely decomposed?

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• Question 4Oct/Nov 2024, paper 41Structured12 marksHas a diagram

  When magnesium nitrate is heated strongly, magnesium oxide is formed. The equation for this reaction is shown. $$2{\mathrm{M}\mathrm{g}(\mathrm{N}\mathrm{O}}_3{)}_2\to 2\mathrm{M}\mathrm{g}\mathrm{O}+4{\mathrm{N}\mathrm{O}}_2+{\mathrm{O}}_2$$ State the change in oxidation number of nitrogen, $\mathrm{N}$, in this reaction.

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