Identification of ions and gases: past paper questions
Real questions on identification of ions and gases
The newest 20 of 74 written questions. Open one to see it on the real paper.
- 5070/42 · October/November 2025 · Q3a(i)[2]
Describe how the student does a flame test.
See it on the paper → - 5070/42 · October/November 2025 · Q3a(ii)[1]
Describe one observation expected in test 2 based on the observation in test 1.
See it on the paper → - 5070/42 · October/November 2025 · Q3a(iii)[3]
Describe one additional test to confirm the identity of the cation in P. Include the result of a positive test. test
See it on the paper → - 5070/42 · October/November 2025 · Q3a(iv)[1]
Identify the cation in P. cation
See it on the paper → - 5070/42 · October/November 2025 · Q3b(i)[1]
Describe the expected colour change in test 3.
See it on the paper → - 5070/42 · October/November 2025 · Q3b(ii)[1]
Predict one other observation made by the student in test 4. A gas is produced in test 4.
See it on the paper → - 5070/42 · October/November 2025 · Q3b(iii)[1]
Predict the identity of the gas produced in test 4.
See it on the paper → - 5070/42 · October/November 2025 · Q3b(iv)[2]
Describe a test to confirm the identity of this gas. Include the result of a positive test. test
See it on the paper → - 5070/42 · October/November 2025 · Q3b(v)[2]
Q contains one cation and one anion. Identify the cation and the anion in Q. cation anion
See it on the paper → - 5070/21 · May/June 2025 · Q1a[1]
is prepared using a precipitation reaction
See it on the paper → - 5070/41 · May/June 2025 · Q3a(i)[2]
The student adds aqueous chlorine to W and concludes that W contains iodide ions. Describe the observation that the student makes that leads to this conclusion. Explain how this shows that W contains iodide ions. observation explanation
See it on the paper → - 5070/41 · May/June 2025 · Q3a(ii)[2]
Describe another test and the observation that confirms that W contains iodide ions. test observation
See it on the paper → - 5070/41 · May/June 2025 · Q3b[2]
The student does a flame test on W and observes a lilac flame. Describe how the student does the flame test on W.
See it on the paper → - 5070/41 · May/June 2025 · Q3c[1]
Identify W.
See it on the paper → - 5070/41 · May/June 2025 · Q3d[2]
X contains one anion and one cation. The student: • • • adds aqueous sodium hydroxide to X in a test-tube warms the mixture holds a piece of damp red litmus paper above the test-tube. The litmus paper does not change colour. State three conclusions that are made from these observations. A white precipitate, soluble in...
See it on the paper → - 5070/41 · May/June 2025 · Q3e[3]
The conclusions in (d) identify cations that may be present in X. test observations Describe another test that the student does and its observations to identify the cation in X.
See it on the paper → - 5070/41 · May/June 2025 · Q3f(ii)[1]
Identify the anion in X.
See it on the paper → - 5070/42 · October/November 2024 · Q3a(i)[3]
Describe how to do a flame test on solution P to confirm the identity of this cation.
See it on the paper → - 5070/42 · October/November 2024 · Q3a(ii)[6]
Solution P contains an anion composed of nitrogen and oxygen. Describe a test to identify the anion in solution P. test observations
See it on the paper → - 5070/42 · October/November 2024 · Q4[1]
Then add aqueous barium nitrate. (i) Identify the cation in solution Q using the observations from tests 1 and 2. (ii) Test 3 is incomplete. Describe what else must be done in test 3 to ensure that the white precipitate observed leads to a valid conclusion about the anion in solution Q. (iii) The student completes test...
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What examiners said
The sulfate test was quite well known. Sulfur dioxide, calcium oxide, carbon monoxide and sodium nitrate were common incorrect responses.
— Examiner report, October/November 2023, 5070/21 Q1(d) (Cambridge)
The anion with a 1– charge was well known. Sodium sulfate was the common incorrect response.
— Examiner report, October/November 2023, 5070/21 Q1(e) (Cambridge)
The test for bromide ions was not well known. Incorrect responses included: alkene with the bromine turning colourless form brown; sodium hydroxide giving a white precipitate and barium nitrate. Yellow precipitate was also common.
— Examiner report, October/November 2023, 5070/21 Q4(c) (Cambridge)
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