Halogen compounds: past paper questions
Real questions on halogen compounds
The newest 20 of 27 written questions, plus 59 multiple-choice. Open one to see it on the real paper.
- 9701/22 · October/November 2025 · Q2d(ii)[1]
Write an equation for the formation of H 3 PO 4 from PCl 5 .
See it on the paper → - 9701/23 · October/November 2025 · Q3d(i)[1]
Identify a suitable reagent for reaction 3.
See it on the paper → - 9701/41 · May/June 2025 · Q10c[2]
When propanoic acid is treated with chlorine gas in the presence of ultraviolet light, a mixture of products is formed. One of these products is 2,2-dichloropropanoic acid. Explain why 2,2-dichloropropanoic acid is stronger than propanoic acid. Refer to the structure of each compound in your answer.
See it on the paper → - 9701/22 · October/November 2024 · Q4c(i)[1]
Complete Fig. 4.1 to: • draw the structure of compound A
See it on the paper → - 9701/41 · October/November 2024 · Q8b(i)[1]
Name the two products formed when phenol reacts with an excess of Br 2 (aq). and (b) (i)
See it on the paper → - 9701/42 · October/November 2024 · Q6a(i)[1]
1-mark question — its maths and diagrams are best seen on the paper.
See it on the paper → - 9701/43 · October/November 2024 · Q7c[1]
Identify compound V.
See it on the paper → - 9701/43 · October/November 2024 · Q7d[1]
Complete the equation for reaction 3. CH 3 COOH + SOCl 2
See it on the paper → - 9701/43 · October/November 2024 · Q7e[1]
Identify compound W.
See it on the paper → - 9701/42 · February/March 2024 · Q4c(i)[1]
Suggest a reagent for step 1.
See it on the paper → - 9701/42 · February/March 2024 · Q5a(i)[1]
Write an equation for the formation of the electrophile for step 1.
See it on the paper → - 9701/42 · February/March 2024 · Q5a(ii)[1]
Complete the mechanism in Fig. 5.2 for step 1, the alkylation of chlorobenzene. Include all relevant curly arrows and charges. Draw the structure of the intermediate. intermediate Cl Cl CH 3 + Fig. 5.2
See it on the paper → - 9701/42 · February/March 2024 · Q5a(iv)[1]
Suggest reagents for the conversion of K to M in steps 3 and 4. step step
See it on the paper → - 9701/42 · February/March 2024 · Q6b(ii)[1]
Identify the reagent used in reaction 2.
See it on the paper → - 9701/23 · October/November 2023 · Q4c(i)[1]
C reacts with HBr to form E. Complete the diagram in Fig. 4.2 to show the mechanism for this reaction. Draw the structure of the organic intermediate. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. C E Br H – Br Fig. 4.2
See it on the paper → - 9701/42 · May/June 2023 · Q5d(i)[1]
Give an equation for the reaction between ethanoic acid and SOBr 2 .
See it on the paper → - 9701/23 · October/November 2022 · Q3a(iv)[1]
the chloride formed from the element with the highest melting point.
See it on the paper → - 9701/21 · May/June 2022 · Q4c(ii)[1]
State the formula of the yellow precipitate produced when X is added to alkaline I 2 (aq).
See it on the paper → - 9701/23 · May/June 2022 · Q5b(i)[1]
educe the number of carbon atoms present in a molecule of Z using Fig. 5.1. D Show your working.
See it on the paper → - 9701/23 · May/June 2022 · Q5b(ii)[1]
Deduce which halogen is present in Z using Fig. 5.1. Explain your answer.
See it on the paper →
What examiners said
The mechanism for the addition of HBr to C, 2-methylbut-2-ene, was quite well answered. Common errors included full charges on the H-Br, instead of a dipole, curly arrows, from C=C to Hδ+ of HBr, arrows starting at one end of the C=C bond and intermediates with both a –ve charge and a partial negative charge.
— Examiner report, October/November 2023, 9701/23 Q4(c)(i) (Cambridge)
This was generally answered well. Common errors included starting with an incorrect formula of ethanoic acid, forming CH3COOBr or H2O as a product.
— Examiner report, May/June 2023, 9701/42 Q5(d)(i) (Cambridge)
SiCl4 was often identified as the chloride formed from the element with the highest melting point.
— Examiner report, October/November 2022, 9701/23 Q3(a)(iv) (Cambridge)
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