Stoichiometry: past paper questions

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• Question 8May/June 2026, paper 11Multiple choice1 mark

  Which definition of the empirical formula of a compound is correct?

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• Question 8Oct/Nov 2025, paper 11Multiple choice1 markHas a diagram

  Aluminium ions, ${\mathrm{A}\mathrm{l}}^{3+}$, react with sulfate ions, ${\mathrm{S}\mathrm{O}}_4^{2-}$, to form aluminium sulfate. Which row shows the correct empirical formula and ionic formula of aluminium sulfate?

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• Question 2Oct/Nov 2024, paper 11Multiple choice1 mark

  When measured under the same conditions of temperature and pressure, which gas diffuses at the same rate as nitrogen?

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• Question 2Oct/Nov 2023, paper 11Multiple choice1 markHas a diagram

  Data about two compounds is given. Both compounds have a simple molecular structure.

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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 9Oct/Nov 2025, paper 11Multiple choice1 mark

  Which statement is correct?

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• Question 3Oct/Nov 2024, paper 11Multiple choice1 mark

  X and Y are both elements, one of which is a non-metal. 1 mole of X is added to 1 mole of Y and they are heated together. X and Y react completely to form substance Z. Substance Z cannot be easily separated to form X and Y. Three statements are given.

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• Question 7Oct/Nov 2023, paper 11Multiple choice1 markHas a diagram

  Which row is correct?

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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 7Oct/Nov 2024, paper 11Multiple choice1 mark

  Chrome alum is a salt that contains two different cations and one anion. The ions present in chrome alum are ${\text{K}}^{+}$, ${\text{Cr}}^{3+}$ and ${\text{SO}}_4^{2-}$. What is the formula of the salt?

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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 8Oct/Nov 2024, paper 11Multiple choice1 mark

  The table gives some information about barium and chlorine. | | relative atomic mass | group in Periodic Table | | :--- | :---: | :---: | | barium | 137 | II | | chlorine | 35.5 | VII | Using this information only, a student makes three statements.

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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 6May/June 2026, paper 12Multiple choice1 mark

  The displayed formula of a compound is shown. What is the empirical formula of the compound?

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• Question 5Oct/Nov 2025, paper 12Multiple choice1 mark

  Which ion has a positive charge?

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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 10Oct/Nov 2023, paper 11Multiple choice1 markHas a diagram

  Three compounds are listed. $$\text{copper(II) nitrate, }\mathrm{C}\mathrm{u}(\mathrm{N}{\mathrm{O}}_3{)}_2$$ $$\text{zinc sulfate, }\mathrm{Z}\mathrm{n}\mathrm{S}{\mathrm{O}}_4$$ $$\text{sodium thiosulfate, }\mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_2{\mathrm{O}}_3$$ Which row shows the element that is present in the greatest percentage by mass in each compound?

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• Question 7May/June 2026, paper 12Multiple choice1 mark

  An ionic compound contains only three elements, X, Y and Z. The compound has a ratio of one atom of X to one atom of Y to three atoms of Z. The average mass of the isotopes of element X is twice the mass of an atom of ${}_6^{12}\text{C}$.

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• Question 7Oct/Nov 2025, paper 12Multiple choice1 mark

  Powdered calcium carbonate reacts with dilute hydrochloric acid to produce calcium chloride, water and carbon dioxide. What is the correct ionic equation, including state symbols, for this reaction?

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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 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 8Oct/Nov 2025, paper 12Multiple choice1 mark

  Which structure shows the carboxylic acid with the lowest relative molecular mass?

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• Question 23Oct/Nov 2024, paper 11Multiple choice1 mark

  Which formula represents the oxide of element Z in Group II of the Periodic Table?

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• Question 37Oct/Nov 2023, paper 11Multiple choice1 mark

  Glycerol is an alcohol with three $-\mathrm{O}\mathrm{H}$ groups per molecule. What is the equation for the combustion of glycerol?

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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 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 38Oct/Nov 2023, paper 11Multiple choice1 markHas a diagram

  Compound X decolourises acidified aqueous potassium manganate(VII). Compound X has the empirical formula ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}$. Some possible structures of X are shown.

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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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