Isotopes: past paper questions
Real questions on isotopes
The newest 20 of 47 written questions. Open one to see it on the real paper.
- 9701/21 · October/November 2025 · Q1a(ii)[1]
Describe how an atom of chromium-54 differs from an atom of chromium-52. Refer to numbers of particles in your answer.
See it on the paper → - 9701/21 · October/November 2025 · Q1a(iii)[1]
The relative isotopic masses of the isotopes of Cr can be determined using mass spectrometry. State what other information is needed to calculate the relative atomic mass, A r , of Cr.
See it on the paper → - 9701/21 · October/November 2025 · Q1a(iv)[1]
Atoms of 52 Cr, 53 Cr and 54 Cr make up more than 95% of naturally occurring chromium atoms. The A r of naturally occurring Cr is 51.996. Suggest what these statements imply about the relative isotopic mass of the fourth stable isotope of chromium.
See it on the paper → - 9701/22 · October/November 2025 · Q1a(i)[1]
Determine the number of protons, neutrons and electrons in an atom of manganese-55. (i)
See it on the paper → - 9701/22 · October/November 2025 · Q1a(ii)[1]
Define isotopes.
See it on the paper → - 9701/22 · October/November 2025 · Q1a(iii)[2]
A sample of manganese from the Moon is found to contain manganese-53 in addition to manganese-55. State the two pieces of information needed to determine the relative atomic mass, A r , of manganese in this sample.
See it on the paper → - 9701/23 · October/November 2025 · Q1a(i)[1]
The most common isotope of Cr is chromium-52. Determine the number of protons, neutrons and electrons in an atom of chromium-52.
See it on the paper → - 9701/23 · October/November 2025 · Q1a(ii)[1]
Describe how an atom of chromium-54 differs from an atom of chromium-52. Refer to numbers of particles in your answer.
See it on the paper → - 9701/23 · October/November 2025 · Q1a(iii)[1]
The relative isotopic masses of the isotopes of Cr can be determined using mass spectrometry. State what other information is needed to calculate the relative atomic mass, A r , of Cr.
See it on the paper → - 9701/23 · October/November 2025 · Q1a(iv)[1]
Atoms of 52 Cr, 53 Cr and 54 Cr make up more than 95% of naturally occurring chromium atoms. The A r of naturally occurring Cr is 51.996. Suggest what these statements imply about the relative isotopic mass of the fourth stable isotope of chromium.
See it on the paper → - 9701/21 · May/June 2025 · Q1c[2]
State the oxidation number of the Period 3 elements bonded to Cl in NaCl and PCl 5 . Explain the difference in the oxidation number.
See it on the paper → - 9701/21 · May/June 2025 · Q2a[1]
Define isotopes.
See it on the paper → - 9701/22 · May/June 2025 · Q2a(ii)[2]
Table 2.1 shows the abundances of two of the isotopes present in the sample of iron. Table 2.1 isotope relative isotopic mass abundance / % 54 Fe 53.9 6.0 56 Fe 55.9 91.9 Use Table 2.1 to calculate the relative isotopic mass of the third isotope of iron in the sample. Show your working. relative isotopic mass = (ii)
See it on the paper → - 9701/22 · February/March 2025 · Q2b(i)[2]
State and explain the variation in ionic radius of the Group 2 elements down the group.
See it on the paper → - 9701/21 · October/November 2024 · Q1b[3]
Table 1.1 gives some details of the stable naturally occurring isotopes of rhodium and iridium. Table 1.1 isotope number of protons number of neutrons 103 45 Rh total number of electron shells 58 191 77 Ir 6 193 77 Ir 6
See it on the paper → - 9701/21 · October/November 2024 · Q1c[2]
Table 1.2 shows the relative abundances of isotopes in a sample of an alloy containing rhodium and iridium only. Table 1.2 (i) isotope relative isotopic mass relative abundance in alloy 103 45 Rh 102.91 50.00 191 77 Ir 190.96 15.18 193 77 Ir 192.96 34.82 Define relative isotopic mass. (ii) Use Table 1.2 to calculate th...
See it on the paper → - 9701/21 · October/November 2024 · Q1c(ii)[2]
Use Table 1.2 to calculate the relative atomic mass, A r , of iridium in the alloy. Give your answer to two decimal places. relative atomic mass of iridium =
See it on the paper → - 9701/22 · October/November 2024 · Q1b(i)[2]
Table 1.1 isotope relative isotopic mass 93 41 Nb 92.91 181 73 Ta 180.95 number of protons number of neutrons Complete Table 1.1. (i)
See it on the paper → - 9701/22 · October/November 2024 · Q1b(ii)[1]
Define relative isotopic mass.
See it on the paper → - 9701/22 · October/November 2024 · Q1b(iii)[1]
181 A sample of pelopium contains 90.9% by mass 93 41 Nb and 9.1% by mass 73 Ta. Calculate the theoretical relative atomic mass of pelopium based on these data and Table 1.1. Give your answer to two decimal places. Show your working.
See it on the paper →
What examiners said
Most candidates were able to identify the increase in ionic radius. The reasoning for this was varied, and imprecise vocabulary was used often (e.g., orbitals, subshells).
— Examiner report, February/March 2025, 9701/22 Q2(b)(i) (Cambridge)
The question contained information regarding the relative intensities of the M and (M + 1) ions, from a mass spectrum of C, which showed a molecular ion peak at 70. Many candidates correctly calculated that C contained 5C atoms but then failed to use this information, in conjunction with the molecular ion peak, 70, to confirm that the molecular formula of C was C5H10.
— Examiner report, October/November 2023, 9701/23 Q4(b) (Cambridge)
Many candidates were able to give the correct formulae at m / e = 164.Very few candidates gave both of the correct options at m / e = 166.
— Examiner report, May/June 2023, 9701/21 Q3(f) (Cambridge)
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