Relative masses of atoms and molecules: 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 9Oct/Nov 2025, paper 11Multiple choice1 mark

  Which statement is correct?

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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 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 8Oct/Nov 2025, paper 12Multiple choice1 mark

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

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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 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 2Oct/Nov 2025, paper 21Structured4 marks

  A sample of sulfur found on the planet Mars contains four isotopes. Table 2.1 shows the percentage abundances of these four isotopes.

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• Question 7Oct/Nov 2023, paper 12Multiple choice1 markHas a diagram

  Which row shows a pair of molecules where the M_r of compound X is exactly half that of compound Y? [A_r: C, 12; Cl, 35.5; H, 1; O, 16] | | X | Y | | :--- |…

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• Question 2Oct/Nov 2025, paper 22Structured4 marks

  A sample of titanium found on an asteroid contains four isotopes. Table 2.1 shows the percentage abundances of these four isotopes.

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• Question 7Oct/Nov 2024, paper 12Multiple choice1 mark

  What is the relative molecular mass, $M_r$, of ethene?

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

  Chrome alum is the common name for a salt which has the formula ${\text{CrK(SO}}_4{)}_2$.

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• Question 1May/June 2025, paper 11Multiple choice1 markHas a diagram

  Four gases are listed. 1 $\mathrm{C}{\mathrm{H}}_4$ 2 $\mathrm{N}{\mathrm{H}}_3$ 3 $\mathrm{C}{\mathrm{O}}_2$ 4 ${\mathrm{N}}_2$ What is the order of their rate of diffusion at room temperature and pressure?

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• Question 8Oct/Nov 2024, paper 12Multiple choice1 mark

  What is the relative molecular mass, $M_r$, of ${\text{N}}_2\text{O}$?

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• Question 7May/June 2023, paper 11Multiple choice1 markHas a diagram

  Three compounds are listed.

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• Question 7May/June 2024, paper 11Multiple choice1 mark

  What is the relative formula mass, $M_{\mathrm{r}}$, of aluminium oxide?

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• Question 3May/June 2023, paper 12Multiple choice1 mark

  Naturally occurring bromine has a relative atomic mass of 80 and consists entirely of two isotopes of relative atomic masses 79 and 81. What can be deduced about naturally occurring bromine from this information only?

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

  An organic compound has an $M_r$ of 88. What is the molecular formula of this compound?

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• Question 4May/June 2024, paper 12Multiple choice1 markHas a diagram

  An element has two isotopes of relative isotopic masses $x$ and $x+2$. The diagram shows the composition of atoms in a sample of the element. What is the relative atomic mass of the sample of the element?

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• Question 8May/June 2023, paper 12Multiple choice1 mark

  Which statements about relative atomic mass and relative molecular mass are correct?

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• Question 9May/June 2025, paper 12Multiple choice1 mark

  Which compound has the highest relative formula mass, $M_{\text{r}}$?

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• Question 10May/June 2023, paper 12Multiple choice1 markHas a diagram

  The diagram shows the structures of the atoms of two elements, X and Z. X and Z are not the atomic symbols for these elements. The elements combine to form a compound. What is the mass of one mole of this compound?

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

  The formula of hydrated sodium carbonate is ${\text{Na}}_2{\text{CO}}_3\cdot 10{\text{H}}_2\text{O}$. What is the percentage composition by mass of oxygen in hydrated sodium carbonate?

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• Question 31May/June 2024, paper 12Multiple choice1 mark

  Ammonium phosphate, $({\mathrm{N}\mathrm{H}}_4{)}_3{\mathrm{P}\mathrm{O}}_4$, may be used as a fertiliser. What is the percentage by mass of elements that improve plant growth in ammonium phosphate?

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• Question 11May/June 2023, paper 12Multiple choice1 mark

  Which compound contains 45.2% nitrogen by mass?

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• Question 30May/June 2025, paper 12Multiple choice1 mark

  Nitrates and ammonium salts are used as fertilisers. Which fertiliser contains the greatest mass of nitrogen in $50\text{ kg}$ of the compound?

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• Question 4May/June 2023, paper 21Structured9 marks

  This question is about compounds that contain phosphorus. The formula for a phosphide ion can be written as ${}_{15}^{31}{\mathrm{P}}^{3-}$. Complete Table 4.1 to show the number of particles in this phosphide ion.

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• Question 4May/June 2023, paper 22Structured9 marks

  This question is about compounds that contain magnesium and nitrogen. The formula for a nitride ion can be written as ${}_7^{15}{\mathrm{N}}^{3-}$. Complete Table 4.1 to show the number of particles in this nitride ion.

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