Formulas: past paper questions
Real questions on formulas
The newest 20 of 53 written questions. Open one to see it on the real paper.
- 9701/41 · May/June 2026 · Q8a(i)[1]
Write an equation for the reaction of CH 3 COOH with SOCl 2 in step 1.
See it on the paper → - 9701/41 · May/June 2026 · Q8a(ii)[1]
State an alternative reagent that reacts with CH 3 COOH to produce CH 3 COCl in step 1.
See it on the paper → - 9701/21 · October/November 2025 · Q3a[1]
Define empirical formula.
See it on the paper → - 9701/23 · October/November 2025 · Q3a[1]
Define empirical formula.
See it on the paper → - 9701/43 · October/November 2025 · Q1a(i)[1]
Write an equation for the decomposition of strontium hydrogencarbonate, Sr(HCO 3 ) 2 .
See it on the paper → - 9701/22 · May/June 2025 · Q1b(i)[1]
Write an equation for each reaction.
See it on the paper → - 9701/22 · May/June 2025 · Q1b(ii)[2]
Describe the appearance of phosphorus( V ) chloride and silicon( IV ) chloride at room temperature. phosphorus( V ) chloride
See it on the paper → - 9701/22 · May/June 2025 · Q1b(iii)[2]
Compare the appearance of the mixtures produced when each reaction is complete.
See it on the paper → - 9701/23 · May/June 2025 · Q4a(ii)[1]
Use Fig. 4.1 to identify the limiting reagent. Explain your answer.
See it on the paper → - 9701/23 · May/June 2025 · Q4a(iv)[2]
The reaction between Na 2 S 2 O 3 (aq) and HCl (aq) is repeated in a second experiment. In this second experiment, 25.0 cm 3 of 0.050 mol dm –3 Na 2 S 2 O 3 (aq) reacts with 0.0020 mol of HCl (aq). Calculate the number of sulfur atoms produced. number of sulfur atoms produced =
See it on the paper → - 9701/22 · February/March 2025 · Q1a(iii)[2]
The third compound of phosphorus and chlorine, W, has a relative molecular mass, M r , between that of PCl 3 and PCl 5 . The compound contains 69.6% by mass of chlorine. Determine the molecular formula of W. molecular formula of W =
See it on the paper → - 9701/22 · February/March 2025 · Q2c(ii)[2]
Complete Table 2.2 to show the numbers of protons and neutrons in the isotopes of magnesium. Table 2.2 isotope number of protons number of neutrons magnesium-25 magnesium-26 magnesium-24
See it on the paper → - 9701/22 · October/November 2024 · Q2a(i)[1]
Write equations for the following reactions. • sodium and oxygen • sulfur and oxygen
See it on the paper → - 9701/23 · October/November 2024 · Q3e(i)[1]
Write an equation for the formation of SiCl 4 from its constituent elements.
See it on the paper → - 9701/43 · October/November 2024 · Q2b(i)[1]
Complete line D. Include state symbols.
See it on the paper → - 9701/53 · October/November 2024 · Q1e(ii)[1]
Use your answer to (i) to calculate the mass, in g, of C 9 H 8 O 4 (s) in the powdered tablets added to the flask in step 2. mass of C 9 H 8 O 4 (s) g
See it on the paper → - 9701/53 · October/November 2024 · Q1e(iii)[1]
Use your answer to (ii) to calculate the percentage by mass of aspirin, C 9 H 8 O 4 (s), in the tablets. If you were unable to obtain an answer to (ii) you may use 0.374 g for the mass of C 9 H 8 O 4 (s). This is not the correct value. percentage by mass C 9 H 8 O 4 (s) in the tablets
See it on the paper → - 9701/53 · October/November 2024 · Q2b(i)[1]
Calculate the mass of C 25 H 30 N 3 Cl (s) needed to prepare solution D. Give your answer to three significant figures. [M r : C 25 H 30 N 3 Cl (s), 407.5] mass of C 25 H 30 N 3 Cl (s) = g
See it on the paper → - 9701/21 · May/June 2024 · Q2d(i)[1]
Use Fig. 2.2 to deduce the empirical formula of boron nitride.
See it on the paper → - 9701/23 · May/June 2024 · Q3c(ii)[2]
100 g of pure boron carbide contains 78.26 g of boron. Calculate the empirical formula of boron carbide. Show your working. empirical formula of boron carbide
See it on the paper →
What examiners said
Many candidates gave the answer of PCl 3 without any working shown. Some attempted trial and error; many had not appreciated that the Mr was between that of PCl 3 and PCl 5.
— Examiner report, February/March 2025, 9701/22 Q1(a)(iii) (Cambridge)
This was well answered, though some confused proton and neutron number, while others gave nucleon number.
— Examiner report, February/March 2025, 9701/22 Q2(c)(ii) (Cambridge)
The addition of ethanoic acid to Ba(OH)2 gave barium ethanoate, (CH3COO)2Ba, as the product. Many candidates appreciated that barium ethanoate was formed but opted to answer using a formula of (CH3COO)Ba, which was not creditworthy.
— Examiner report, October/November 2023, 9701/21 Q2(a)(iv) (Cambridge)
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