plumiRelative masses and mass spectra: OCR A‑Level Chemistry A questions
OCR A-Level Chemistry A past-paper questions on 2.1.1.2 Relative masses and mass spectra, 2016–2025, with mark schemes and examiner’s reports where available.
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Q1(a)(ii)
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All 19 questions on Relative masses and mass spectra, as a list
- June 2025, Paper 3, Q1(a)(ii) (3 marks): Explain why there are peaks with m/z values of 158, 160 and 162 and predict their relative abundances. Explanation Relative abundances [3]
- June 2025, AS Paper 1, Q21(b) (2 marks): The mass spectrum of a sample of magnesium is shown below. 75.45% Relative abundance 15.21% 9.34% 24 25 26 m / z Calculate the relative atomic mass of magnesium
- June 2024, AS Paper 1, Q21(a) (2 marks): A sample of iron is isolated from a meteorite and analysed by mass spectrometry. The mass spectrum shows peaks with the relative abundances below. 54Fe 56Fe 57F
- June 2023, AS Paper 2, Q1(a)(i) (2 marks): Calculate the relative atomic mass of titanium in the sample. Give your answer to 2 decimal places. relative atomic mass = [2]
- June 2022, Paper 3, Q1(b)(i) (1 mark): What are the percentage compositions of copper and zinc in the brass sample? Cu = % Zn = % [1]
- June 2022, Paper 3, Q1(b)(ii) (2 marks): Calculate the relative atomic mass of zinc in the sample of brass. Give your answer to 2 decimal places. relative atomic mass = [2]
- June 2022, AS Paper 1, Q22(a) (2 marks): The relative atomic mass of a sample of osmium can be determined from its mass spectrum, shown below. 43.89% 27.23% relative abundance 16.75% (%) 12.13% 185 186
- November 2021, AS Paper 1, Q21(c) (2 marks): The relative atomic mass of an element can be determined from its mass spectrum. The table shows the results of a mass spectrum of a sample of sulfur, S. Isotop
- November 2020, Paper 1, Q16(a) (1 mark): Relative atomic mass is defined as ‘the weighted mean mass compared with 1/12th mass of carbon-12’. Explain what is meant by the term weighted mean mass. [1]
- November 2020, AS Paper 1, Q21(c)(i) (2 marks): Calculate the relative atomic mass of chlorine. Give your answer to 2 decimal places. relative atomic mass = [2]
- November 2020, AS Paper 1, Q21(c)(ii) (2 marks): The mass spectrum of chlorine, Cl 2, also contains three molecular ion, M+, peaks. One of the M+ peaks has an m /z value of 72. Suggest why an M+ peak at m /z =
- June 2019, Paper 1, Q16(b) (2 marks): A sample of magnesium, Ar = 24.305, is found to consist of three isotopes. The accurate relative isotopic masses and % abundances of two of the isotopes are sho
- June 2019, AS Paper 2, Q1(a)(i) (2 marks): Explain what is meant by the term relative atomic mass of an element. [2]
- June 2019, AS Paper 2, Q1(a)(ii) (2 marks): A sample of strontium has a relative atomic mass of 87.73. The sample consists of: • 82.9% Sr-88 • 6.9% Sr-87 • one other isotope. Determine the other isotope o
- June 2018, Paper 1, Q1 (1 mark): A sample of boron contains the isotopes 10B and 11B. 1 The relative atomic mass of the boron sample is 10.8. What is the percentage of 11B atoms in the sample o
- June 2018, AS Paper 1, Q21(a)(ii) (2 marks): A sample of silicon is analysed by mass spectrometry. The mass spectrum shows peaks with the relative abundances below. 28Si • 92.23% 29Si • 4.68% 30Si • 3.09%
- June 2017, AS Paper 1, Q22(a)(i) (2 marks): The species causing the peaks in the mass spectrum are 1+ ions of magnesium. Complete the table to show the number of protons, neutrons and electrons in each 1+
- June 2017, AS Paper 1, Q22(a)(ii) (2 marks): Calculate the relative atomic mass of the magnesium in the sample. Give your answer to two decimal places. relative atomic mass = [2]
- June 2016, AS Paper 1, Q21(b)(i) (2 marks): Calculate the relative atomic mass of the copper used to make the coins. Give your answer to two decimal places. relative atomic mass = [2]
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