0654.C3.2.02 — Define relative molecular mass, Mr, as the sum of the relative atomic masses. Relative formula mass, Mr, will be used for ionic compounds: past paper questions

Real questions on 0654.c3.2.02 — define relative molecular mass, mr, as the sum of the relative atomic masses. relative formula mass, mr, will be used for ionic compounds

The newest 5 of 5 written questions. Open one to see it on the real paper.

1. 0654/31 · May/June 2026 · Q8a[2]

   The formula of sulfuric acid is H,SO,. Calculate the relative molecular mass M, of sulfuric acid. [A, : H, 1; 0, 16; S, 32] relative molecular Mass este

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2. 0654/32 · May/June 2026 · Q7a(ii)[2]

   Calculate the relative molecular mass, M,, of ethene. [A,: ©, 12; H, 1] relative Molecular MASS ects

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3. 0654/31 · October/November 2025 · Q6b[1]

   Determine the relative molecular mass, M r , of methane, CH 4 . relative molecular mass, M r = [A r : C, 12; H, 1]

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4. 0654/32 · May/June 2025 · Q6a(iv)[1]

   Determine the relative molecular mass, M r , of ethanol. [A r : C, 12; H, 1; O, 16] relative molecular mass =

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5. 0654/43 · October/November 2019 · Q2c(iii)[1]

   Show that the relative molecular mass of ammonia, NH 3 , is 17. [A r : H,1; N,14]

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What examiners said

A common incorrect answer was 29 (the sum of the different types of atom present) with no attempt to look at how many of each type of atom were in the formula. Familiarity with what a chemical formula represents is fundamental to chemistry and it was clear a number of candidates either did not look at the formula or did not understand it.

— Examiner report, May/June 2025, 0654/32 Q6(a)(iv) (Cambridge)

The majority of candidates were able to verify the value for the relative molecular mass of ammonia.

— Examiner report, October/November 2019, 0654/43 Q2(c)(iii) (Cambridge)