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The halogens

Past-paper questions pack

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Questions are numbered; the mark schemes (the answer key) follow on separate pages so the question pages can be handed out alone. www.chemistryaleveltutor.com

OCR AS and A-level Chemistry past-paper questions since 2016 · 61 parts · mark schemes follow the questions · www.chemistryaleveltutor.com · Questions and mark schemes © OCR

1. June 2025 · Paper 1 · Q7 · 1 marks ·
7 The table below shows the boiling points of some hydrogen halides. Hydrogen halide Boiling point / K HCl 188 HBr 206 HI 238 What is the best explanation for the trend in boiling points from HCl to HI? A The strength of the covalent bonds increases. B The strength of the hydrogen bonds increases. C The strength of the induced dipole–dipole interactions (London forces) increases. D The strength of the permanent dipole–dipole interactions increases. Your answer [1]
2. June 2025 · Paper 1 · Q16(c) · 3 marks ·
(c) A student adds an aqueous solution of bromine, Br2(aq), to two test tubes. The student adds aqueous sodium iodide, NaI(aq), to the Br2(aq) in one test tube, and aqueous sodium chloride, NaCl (aq), to the Br2(aq) in the other test tube. Complete the table to show the student's observations. Write ionic equation(s) for any reaction(s) that take place. Solutions Observations ................................................................................................ Br2(aq) + NaI(aq) ............................................................................................... ................................................................................................ Br2(aq) + NaCl (aq) ............................................................................................... Ionic equation(s) ............................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [3]
3. June 2025 · Paper 1 · Q19(b)(ii) · 3 marks ·
(ii) When heated, aqueous HNO2 disproportionates. The equation is shown below. 3HNO2(aq) HNO3(aq) + 2NO(g) + H2O(l) • What is meant by disproportionation? • Use oxidation numbers to show that disproportionation has taken place. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [3]
4. June 2025 · AS Paper 1 · Q22(a) · 3 marks ·
22 This question is about halogens and their compounds. (a) An aqueous solution of bromine reacts with cold aqueous sodium hydroxide in a disproportionation reaction. The equation is shown below. Br2(aq) + 2NaOH(aq) NaBr(aq) + NaBrO(aq) + H2O(l) Explain what is meant by the term disproportionation. Use the equation above and oxidation numbers. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [3]
5. June 2025 · AS Paper 1 · Q22(b)(i) · 3 marks ·
(b) An aqueous solution of chlorine also reacts with cold, aqueous sodium hydroxide. The reaction is more vigorous than the reaction of Br2(aq) with NaOH(aq) in (a). (i) Explain why chlorine reacts more vigorously than bromine. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [3]
6. June 2025 · AS Paper 1 · Q22(b)(ii) · 1 marks ·
(ii) Chlorine is used in water treatment. State one disadvantage of treating water with chlorine. .......................................................................................................................................................... .................................................................................................................................................... [1]
7. June 2025 · AS Paper 1 · Q22(c) · 4 marks ·
(c) A group of students is provided with aqueous solutions of sodium chloride, sodium bromide and sodium iodide in three unlabelled bottles. Explain how the students can identify which bottle contains each aqueous solution using precipitation reactions and the solubility of any precipitate formed. Include an ionic equation in your answer. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [4]
8. June 2025 · Paper 3 · Q4(a)(ii) · 7 marks ·
(ii) Complete the flowchart by adding formulae in the boxes. ................. ................. white precipitate white precipitate Ag+(aq) Ba2+(aq) ................. ................. ................. acidic solution containing three ions Cl 2(aq)/H2O(I) H+(aq)/H2S(g) SO3 2–(aq) ................. ................. yellow solid colourless neutral liquid H+/Cr2O7 2–(aq) Ba2+(aq) green solution white precipitate [7]
9. June 2024 · Paper 1 · Q5 · 1 marks ·
5 Which statement explains the trend in boiling points down the halogens group? A The bond enthalpy of the covalent bonds increases. B The halogens become less electronegative. C The induced dipole–dipole interactions (London forces) become stronger. D The reactivity of the halogens decreases. Your answer [1]
10. June 2024 · Paper 1 · Q6 · 1 marks ·
6 Which equation does not represent a disproportionation reaction? A Cl 2 + H2O HCl O + HCl B Cl 2 + 2NaOH NaCl O + NaCl + H2O C 4KCl O3 KCl + 3KCl O4 D 4HCl + MnO2 MnCl 2 + Cl 2 + 2H2O Your answer [1]
11. June 2024 · AS Paper 1 · Q8 · 1 marks ·
8 In the UK, water companies typically treat drinking water with chlorine gas at a concentration of 0.500 mg dm–3 or less. Which statement about UK drinking water is correct? A Chlorine in drinking water can catalyse the breakdown of ozone. B Chlorine may form toxic chlorinated hydrocarbons. C Drinking water with a chlorine gas concentration of 0.500 mg dm–3 contains 2.12 × 1018 chlorine molecules in each dm3. D In hot weather, chlorine can vaporise from drinking water to cause global warming. Your answer [1]
12. June 2024 · AS Paper 1 · Q9 · 1 marks ·
9 Which reaction does not show disproportionation of chlorine? A MnO2 + 4HCl MnCl 2 + Cl 2 + 2H2O B Cl 2 + H2O HCl + HCl O C 2Cl O2 + 2NaOH NaCl O2 + NaCl O3 + H2O D 2NaOH + Cl 2 NaCl + NaCl O + H2O Your answer [1]
13. June 2024 · Paper 1 · Q14 · 1 marks ·
14 Chlorine has the electron configuration [Ne]3s23p5. Which statement(s) about chlorine is/are correct when it reacts in redox reactions? 1 It can gain one electron to form 1– ions. 2 It can lose its 3s2 electrons to form 2+ ions. 3 It can lose its 3p5 electrons to form 5+ ions. A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
14. June 2024 · Paper 1 · Q20(a)(i) · 1 marks ·
20 This question is about elements in the periodic table. (a) Chlorine has many uses. (i) Chlorine is used to treat water in large-scale water treatment plants. Suggest why chlorine is added to water in large-scale water treatment plants. .......................................................................................................................................................... ..................................................................................................................................................... [1]
15. June 2024 · Paper 1 · Q20(a)(ii) · 2 marks ·
(ii) Sea water contains aqueous bromide ions. Chlorine is used to extract bromine from sea water. Construct the ionic equation for this reaction and explain why chlorine is suitable for this extraction of bromine but iodine is not. Equation ........................................................................................................................................... Explanation ...................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [2]
16. June 2024 · AS Paper 2 · Q2(a)(iii) · 2 marks ·
(iii) Mg forms 2+ ions but Cl usually forms 1– ions in their reactions. Explain why. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... ..................................................................................................................................................... [2]
17. June 2024 · Paper 3 · Q2(b)(i) · 1 marks ·
(b) Compound A is a chloride of a Period 3 element. A student carries out the 2 steps below to find the formula of compound A. Step 1 The student adds 5.00 × 10–4 mol of compound A to water. A colourless solution is formed. Step 2 The colourless solution reacts with exactly 60.0 cm3 of 2.50 × 10–2 mol dm–3 AgNO3(aq) to form a white precipitate. (i) Write an ionic equation, with state symbols, for the reaction in Step 2. ..................................................................................................................................................... [1]
18. June 2023 · AS Paper 1 · Q1 · 1 marks · AO1
1 Which statement explains the trend in boiling points down the halogens group? A Covalent bonds become stronger. B Induced dipole–dipole interactions (London forces) become stronger. C Ionic bonds become stronger. D Permanent dipole–dipole interactions become stronger. Your answer [1]
19. June 2023 · Paper 1 · Q11 · 1 marks · AO2
11 A student adds aqueous potassium carbonate to one test tube and aqueous silver nitrate to a second test tube. The student adds dilute hydrochloric acid to each test tube. Which row has the correct observations? Aqueous potassium carbonate Aqueous silver nitrate A no change precipitate B no change no change C effervescence no change D effervescence precipitate Your answer [1]
20. June 2023 · AS Paper 2 · Q2(b)(iii) · 2 marks · AO3
(iii) The student changes the method in 2(b). In step 2, the student adds an excess of silver nitrate solution, AgNO3(aq), instead of Na2SO4(aq). Explain whether this change would allow the student to determine the percentage by mass of NaCl (s) in the mixture. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
21. June 2023 · AS Paper 2 · Q3(a) · 6 marks · AO1, 2
3 This question is about halogens and halogen compounds. (a)* Seawater contains very small quantities of dissolved iodide ions. The concentration of potassium iodide, KI, in seawater is 0.150 g dm–3. Iodine can be extracted by bubbling chlorine gas through seawater. Explain why chlorine is more reactive than iodine and determine the volume, in dm3, of seawater that is needed to manufacture 1.00 tonne of iodine, I2. [6] ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................
22. June 2023 · AS Paper 2 · Q3(b) · 3 marks · AO1, 2
(b) Chlorine reacts with calcium hydroxide to form Ca(OCl )2, which is the active ingredient in bleaching powder. 2Cl 2 + 2Ca(OH)2 CaCl 2 + Ca(OCl )2 + 2H2O This is a disproportionation reaction. State what is meant by disproportionation and use oxidation numbers to show that disproportionation has taken place. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3]
23. June 2023 · AS Paper 2 · Q3(d)(i) · 2 marks · AO1
(d) The student sets up an experiment to compare the rates of hydrolysis of 2-bromopropane and 2-iodopropane. The student uses the method below. Step 1 Place two test tubes, both containing aqueous silver nitrate and ethanol, in a water bath at 60 °C. Step 2 Add five drops of 2-bromopropane to one test tube and five drops of 2-iodopropane to the other test tube. Step 3 Record the time taken for a precipitate to appear in each test tube. (i) Complete the table below to show the formula and colour of each precipitate formed. Haloalkane Formula of precipitate Colour of precipitate 2-bromopropane 2-iodopropane [2]
24. June 2023 · Paper 3 · Q1(g) · 1 marks · AO1
(g) The element that forms 1– ions most readily. ................... [1]
25. June 2022 · Paper 1 · Q1 · 1 marks · AO2
1 An aqueous solution contains a mixture of chloride, bromide and iodide ions. AgNO3(aq) is added to this mixture, followed by an excess of dilute NH3(aq). The resulting mixture is then filtered. Which compound(s) is/are present in the residue on the filter paper? A AgCl only B AgCl and AgBr C AgBr only D AgBr and AgI Your answer [1]
26. June 2022 · AS Paper 1 · Q10 · 1 marks · AO1
10 What is the correct explanation for the trend in the boiling points of chlorine, bromine, and iodine down the group? A Bond enthalpy increases. B Chemical reactivity decreases. C Electronegativity decreases. D London forces increase. Your answer [1]
27. June 2022 · AS Paper 1 · Q24(a)(i) · 1 marks · AO1
24 This question is about halogens and practical tests. (a) Chlorine gas reacts with dilute sodium hydroxide, NaOH(aq). This is a disproportionation reaction. One of the products has the formula NaCl O. (i) What is meant by the term disproportionation? ........................................................................................................................................... ...................................................................................................................................... [1]
28. June 2022 · AS Paper 1 · Q24(a)(ii) · 3 marks · AO2
(ii) Construct the equation for the reaction of chlorine with dilute sodium hydroxide. Use your equation to explain that disproportionation has taken place. Equation ............................................................................................................................ Explanation ....................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... [3]
29. June 2022 · AS Paper 1 · Q24(b) · 5 marks · AO3
(b) A student is supplied with aqueous solutions of ionic compounds B and C. Compound B is a chloride, bromide or iodide of a Group 1 element. Compound C is a chloride, bromide or iodide of a Group 2 element. The molar masses of B and C are both in the range 100–115 g mol–1. Use this information and test-tube tests to show how the student could identify the halide present in B and C and the formulae of B and C. Explain your reasoning. In your answer, include observations, colours and equations. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [5]
30. June 2022 · Paper 3 · Q2(a)(ii) · 3 marks · AO1, 2
(ii) Calcium hypochlorite, Ca(Cl O)2, is heated. The Ca(Cl O)2 decomposes to form CaCl 2 and Ca(Cl O3)2. This is a disproportionation reaction. Write an equation for this decomposition and explain, using oxidation numbers, why this is a disproportionation reaction. equation ............................................................................................................................ explanation ........................................................................................................................ ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
31. June 2022 · Paper 3 · Q4(b)(i) · 1 marks · AO3
(b) The students investigate how addition of aqueous silver nitrate, AgNO3(aq), affects the equilibrium position in Equilibrium 4.1. The graph shows the changes in the equilibrium concentrations of CoCl 4 2–, Cl – and [Co(H2O)6]2+ after addition of the AgNO3(aq). The AgNO3(aq) is added at time = t1. CoCl4 2– Cl – Concentration [Co(H2O)6]2+ 0 t1 Time (i) Explain why the Cl – concentration drops sharply at time = t1. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
32. November 2021 · Paper 1 · Q13 · 1 marks ·
13 Which statement(s) explain(s) the trend in boiling points down the halogens group? 1: The induced dipole–dipole interactions (London forces) become stronger. 2: The covalent bonds become stronger. 3: The permanent dipole–dipole interactions become stronger. A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
33. November 2021 · Paper 1 · Q19(b)(i) · 2 marks · AO2
(b) In acid conditions, MnO4 2–(aq) disproportionates to form MnO2(s) and MnO4 –(aq). (i) Explain, in terms of oxidation numbers, why disproportionation has taken place. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
34. November 2021 · AS Paper 1 · Q23(a) · 1 marks · AO1
23 This question is about halogens. (a) Chlorine is used to kill bacteria in drinking water. State one risk in using chlorine in drinking water. ................................................................................................................................................... .............................................................................................................................................. [1]
35. November 2021 · AS Paper 1 · Q23(d) · 5 marks · AO1, 2, 3
(d) A student investigates the trend in reactivity of the halogens Cl 2, Br2 and I2. The student is supplied with: • solutions of Cl 2, Br2 and I2 in cyclohexane (an organic solvent) • aqueous solutions of the halides: NaCl , NaBr and NaI. The colours of the halogen solutions in cyclohexane are shown below. Halogen Cl 2 Br2 I2 Colour in cyclohexane Pale green Orange Violet Plan an experiment on a test tube scale that would show the trend in the reactivity of the halogens Cl 2, Br2 and I2. Include all the expected observations and an ionic equation for one of the reactions. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [5]
36. November 2020 · Paper 1 · Q21(a) · 5 marks · AO1, 2
21 This question is about halogens. (a) A student adds a solution of bromine in an organic solvent to two test tubes. The student adds aqueous sodium chloride to one test tube, and aqueous sodium iodide to the other test tube. The student shakes the mixtures, allows them to settle, and records the colour of the organic layer in each mixture. Sodium halide Colour of organic layer Sodium chloride orange Sodium iodide violet Explain how the student’s results provide evidence for the trend in reactivity of the halogens down group 17(7) and write an ionic equation for any reaction that takes place. Use your chemical knowledge to explain the trend in reactivity. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [5]
37. November 2020 · Paper 1 · Q21(b) · 1 marks · AO1
(b) Chlorine is used in water treatment. State one benefit and one risk of using chlorine in water treatment. Benefit ...................................................................................................................................... ................................................................................................................................................... Risk ........................................................................................................................................... ................................................................................................................................................... [1]
38. November 2020 · AS Paper 2 · Q1(c) · 6 marks · AO1, 2, 3
(c)* A student is provided with samples of three nickel compounds. One sample is nickel(II) bromide, another is nickel(II) sulfate and the third is nickel(II) carbonate. The student doesn’t know which sample is which. Describe the tests that the student could carry out to identify the anion (negative ion) in each sample, and write equations for any reactions. [6] ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Additional answer space if required ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................
39. November 2020 · AS Paper 2 · Q3(d)(ii) · 3 marks · AO1, 2
(ii) This reaction is an example of disproportionation. Use oxidation numbers to explain why. Include the meaning of the term disproportionation. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
40. June 2019 · AS Paper 1 · Q1 · 1 marks · AO1
1 Which statement about the periodic table is not correct? A The elements are arranged in groups with similar chemical properties. B The elements are arranged in periods with repeating trends in properties. C The elements are arranged in order of increasing atomic number. D The elements in the halogen group increase in reactivity down the group. Your answer [1]
41. June 2019 · Paper 1 · Q2 · 1 marks · AO1
2 Which statement about the reactions of halogens with halide ions is correct? A I2(aq) can oxidise Br−(aq). B Cl 2(aq) can reduce Br−(aq). C Br−(aq) can reduce Cl 2(aq). D Cl −(aq) can oxidise I2(aq). Your answer [1]
42. June 2019 · AS Paper 1 · Q9 · 1 marks · AO2
9 Which reaction shows chlorine only being oxidised? A Cl 2 + H2O → HCl + HCl O B 2Cl O2 + 2NaOH → NaCl O2 + NaCl O3 + H2O C 4KCl O3 → 3KCl O4 + KCl D MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O Your answer [1]
43. June 2019 · AS Paper 1 · Q23(a) · 3 marks · AO1
23 This question is about halogens and halides. (a) The boiling points of the halogens are shown in the table. Boiling point Halogen / K fluorine 85 chlorine 239 bromine 332 iodine 457 astatine 503 Explain the trend in boiling points of the halogens. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3]
44. June 2019 · AS Paper 1 · Q23(b) · 5 marks · AO3
(b) You are supplied with a sample of ammonium bromide. Describe simple tests that would identify the cation and anion present in ammonium bromide. Include reagents, expected observations and relevant equations. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [5]
45. June 2018 · Paper 1 · Q20(a) · 3 marks ·
20 This question is about the halogen group of elements and some of their compounds. (a) The halogens show trends in their properties down the group. The boiling points of three halogens are shown below. Halogen Boiling point / °C Chlorine –35 Bromine 59 Iodine 184 Explain why the halogens show this trend in boiling points. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3]
46. June 2018 · AS Paper 1 · Q23(a)(ii) · 2 marks ·
(ii) At the end of the experiment, the student adds a few drops of aqueous sodium chloride to the reaction mixture in the polystyrene cup to test whether all the aqueous silver nitrate has reacted. Explain how the results would show whether all the aqueous silver nitrate has reacted. Include an equation with state symbols in your answer. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
47. June 2018 · AS Paper 2 · Q3(a)(i) · 1 marks ·
3 This question is about halogens. (a) Bromine is used to extract iodine from a solution containing iodide ions. (i) Write an ionic equation for the reaction. ...................................................................................................................................... [1]
48. June 2018 · AS Paper 2 · Q3(a)(ii) · 3 marks ·
(ii) Explain why iodine is less reactive than bromine. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
49. June 2018 · AS Paper 2 · Q3(b)(i) · 3 marks ·
(b) Iodine can be used for the small-scale purification of drinking water. (i) Iodine reacts with water as shown below. I2 + H2O HI + HIO Using oxidation numbers, explain why this reaction is a disproportionation. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
50. June 2018 · AS Paper 2 · Q3(b)(ii) · 1 marks ·
(ii) Chlorine is used to purify water on a large scale. State one disadvantage of using chlorine for the purification of drinking water. ........................................................................................................................................... ...................................................................................................................................... [1]
51. June 2018 · AS Paper 2 · Q3(d)(i) · 1 marks ·
(d) ‘Enthalpy change of vaporisation’ is the enthalpy change when one mole of a substance changes from a liquid to a gas at its boiling point. (i) Write an equation, including state symbols, to represent the enthalpy change of vaporisation of bromine. ...................................................................................................................................... [1]
52. June 2018 · AS Paper 2 · Q3(d)(ii) · 1 marks ·
(ii) Suggest whether the enthalpy change of vaporisation of bromine is exothermic or endothermic. Explain your answer. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
53. June 2018 · Paper 3 · Q1(a)(v) · 1 marks ·
(v) An element which reacts with water to form an acidic solution. .............................. [1]
54. June 2017 · Paper 1 · Q8 · 1 marks ·
8 Four pairs of solutions are mixed. Which pair of solutions forms a white precipitate? A NH4Cl (aq) and NaOH(aq) B KBr(aq) and AgNO3(aq) C FeCl 3(aq) and NH3(aq) D Cr2(SO4)3(aq) and BaCl 2(aq) Your answer [1]
55. June 2017 · AS Paper 1 · Q9 · 1 marks ·
9 What is the best explanation for the trend in boiling points down the halogens group? A The covalent bonds become stronger. B The hydrogen bonds become stronger. C The permanent dipole–dipole interactions become stronger. D The induced dipole–dipole interactions (London forces) increase. Your answer [1]
56. June 2017 · AS Paper 1 · Q10 · 1 marks ·
10 Which silver compound is insoluble in concentrated NH3(aq)? A AgNO3 B AgCl C AgBr D AgI Your answer [1]
57. June 2017 · Paper 1 · Q17(c)(i) · 3 marks ·
(c) On gently heating, the compound KCl O3 reacts as shown in the equation. 4KCl O3(s) KCl (s) + 3KCl O4(s) This reaction is an example of disproportionation. (i) State what is meant by disproportionation and use oxidation numbers to show that disproportionation has taken place. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3]
58. June 2016 · AS Paper 1 · Q23(a)(ii) · 2 marks · AO1
(ii) Write an ionic equation for this reaction and state why this reaction takes place in terms of reactivity of the halogens. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
59. June 2016 · AS Paper 1 · Q23(b) · 1 marks · AO1
(b) Chlorine is used in water treatment. State one benefit and one risk of chlorine in water treatment. Benefit ....................................................................................................................................... ................................................................................................................................................... Risk ........................................................................................................................................... .............................................................................................................................................. [1]
60. June 2016 · AS Paper 1 · Q23(c)(i) · 1 marks · AO1
(c) Precipitation reactions can be used to distinguish between halide ions. (i) State the reagent needed for these precipitation reactions. ...................................................................................................................................... [1]
61. June 2016 · AS Paper 1 · Q23(c)(ii) · 1 marks · AO1
(ii) How would the appearance of the precipitates allow you to distinguish between chloride, bromide and iodide ions? Chloride ............................................................................................................................. Bromide ............................................................................................................................. Iodide ................................................................................................................................ [1]

Mark schemes

1. June 2025 · Paper 1 · Q7
Mark scheme June 2025 Paper 1 Q7
2. June 2025 · Paper 1 · Q16(c)
Mark scheme June 2025 Paper 1 Q16(c)
3. June 2025 · Paper 1 · Q19(b)(ii)
Mark scheme June 2025 Paper 1 Q19(b)(ii)
4. June 2025 · AS Paper 1 · Q22(a)
Mark scheme June 2025 Paper 1 Q22(a)
5. June 2025 · AS Paper 1 · Q22(b)(i)
Mark scheme June 2025 Paper 1 Q22(b)(i)
6. June 2025 · AS Paper 1 · Q22(b)(ii)
Mark scheme June 2025 Paper 1 Q22(b)(ii)
7. June 2025 · AS Paper 1 · Q22(c)
Mark scheme June 2025 Paper 1 Q22(c)
8. June 2025 · Paper 3 · Q4(a)(ii)
Mark scheme June 2025 Paper 3 Q4(a)(ii)
9. June 2024 · Paper 1 · Q5
Mark scheme June 2024 Paper 1 Q5
10. June 2024 · Paper 1 · Q6
Mark scheme June 2024 Paper 1 Q6
11. June 2024 · AS Paper 1 · Q8
Mark scheme June 2024 Paper 1 Q8
12. June 2024 · AS Paper 1 · Q9
Mark scheme June 2024 Paper 1 Q9
13. June 2024 · Paper 1 · Q14
Mark scheme June 2024 Paper 1 Q14
14. June 2024 · Paper 1 · Q20(a)(i)
Mark scheme June 2024 Paper 1 Q20(a)(i)
15. June 2024 · Paper 1 · Q20(a)(ii)
Mark scheme June 2024 Paper 1 Q20(a)(ii)
16. June 2024 · AS Paper 2 · Q2(a)(iii)
Mark scheme June 2024 Paper 2 Q2(a)(iii)
17. June 2024 · Paper 3 · Q2(b)(i)
Mark scheme June 2024 Paper 3 Q2(b)(i)
18. June 2023 · AS Paper 1 · Q1
Mark scheme June 2023 Paper 1 Q1
19. June 2023 · Paper 1 · Q11
Mark scheme June 2023 Paper 1 Q11
20. June 2023 · AS Paper 2 · Q2(b)(iii)
Mark scheme June 2023 Paper 2 Q2(b)(iii)
21. June 2023 · AS Paper 2 · Q3(a)
Mark scheme June 2023 Paper 2 Q3(a)
22. June 2023 · AS Paper 2 · Q3(b)
Mark scheme June 2023 Paper 2 Q3(b)
23. June 2023 · AS Paper 2 · Q3(d)(i)
Mark scheme June 2023 Paper 2 Q3(d)(i)
24. June 2023 · Paper 3 · Q1(g)
Mark scheme June 2023 Paper 3 Q1(g)
25. June 2022 · Paper 1 · Q1
Mark scheme June 2022 Paper 1 Q1
26. June 2022 · AS Paper 1 · Q10
Mark scheme June 2022 Paper 1 Q10
27. June 2022 · AS Paper 1 · Q24(a)(i)
Mark scheme June 2022 Paper 1 Q24(a)(i)
28. June 2022 · AS Paper 1 · Q24(a)(ii)
Mark scheme June 2022 Paper 1 Q24(a)(ii)
29. June 2022 · AS Paper 1 · Q24(b)
Mark scheme June 2022 Paper 1 Q24(b)
30. June 2022 · Paper 3 · Q2(a)(ii)
Mark scheme June 2022 Paper 3 Q2(a)(ii)
31. June 2022 · Paper 3 · Q4(b)(i)
Mark scheme June 2022 Paper 3 Q4(b)(i)
32. November 2021 · Paper 1 · Q13
Mark scheme November 2021 Paper 1 Q13
33. November 2021 · Paper 1 · Q19(b)(i)
Mark scheme November 2021 Paper 1 Q19(b)(i)
34. November 2021 · AS Paper 1 · Q23(a)
Mark scheme November 2021 Paper 1 Q23(a)
35. November 2021 · AS Paper 1 · Q23(d)
Mark scheme November 2021 Paper 1 Q23(d)
36. November 2020 · Paper 1 · Q21(a)
Mark scheme November 2020 Paper 1 Q21(a)
37. November 2020 · Paper 1 · Q21(b)
Mark scheme November 2020 Paper 1 Q21(b)
38. November 2020 · AS Paper 2 · Q1(c)
Mark scheme November 2020 Paper 2 Q1(c)
39. November 2020 · AS Paper 2 · Q3(d)(ii)
Mark scheme November 2020 Paper 2 Q3(d)(ii)
40. June 2019 · AS Paper 1 · Q1
Mark scheme June 2019 Paper 1 Q1
41. June 2019 · Paper 1 · Q2
Mark scheme June 2019 Paper 1 Q2
42. June 2019 · AS Paper 1 · Q9
Mark scheme June 2019 Paper 1 Q9
43. June 2019 · AS Paper 1 · Q23(a)
Mark scheme June 2019 Paper 1 Q23(a)
44. June 2019 · AS Paper 1 · Q23(b)
Mark scheme June 2019 Paper 1 Q23(b)
45. June 2018 · Paper 1 · Q20(a)
Mark scheme June 2018 Paper 1 Q20(a)
46. June 2018 · AS Paper 1 · Q23(a)(ii)
Mark scheme June 2018 Paper 1 Q23(a)(ii)
47. June 2018 · AS Paper 2 · Q3(a)(i)
Mark scheme June 2018 Paper 2 Q3(a)(i)
48. June 2018 · AS Paper 2 · Q3(a)(ii)
Mark scheme June 2018 Paper 2 Q3(a)(ii)
49. June 2018 · AS Paper 2 · Q3(b)(i)
Mark scheme June 2018 Paper 2 Q3(b)(i)
50. June 2018 · AS Paper 2 · Q3(b)(ii)
Mark scheme June 2018 Paper 2 Q3(b)(ii)
51. June 2018 · AS Paper 2 · Q3(d)(i)
Mark scheme June 2018 Paper 2 Q3(d)(i)
52. June 2018 · AS Paper 2 · Q3(d)(ii)
Mark scheme June 2018 Paper 2 Q3(d)(ii)
53. June 2018 · Paper 3 · Q1(a)(v)
Mark scheme June 2018 Paper 3 Q1(a)(v)
54. June 2017 · Paper 1 · Q8
Mark scheme June 2017 Paper 1 Q8
55. June 2017 · AS Paper 1 · Q9
Mark scheme June 2017 Paper 1 Q9
56. June 2017 · AS Paper 1 · Q10
Mark scheme June 2017 Paper 1 Q10
57. June 2017 · Paper 1 · Q17(c)(i)
Mark scheme June 2017 Paper 1 Q17(c)(i)
58. June 2016 · AS Paper 1 · Q23(a)(ii)
Mark scheme June 2016 Paper 1 Q23(a)(ii)
59. June 2016 · AS Paper 1 · Q23(b)
Mark scheme June 2016 Paper 1 Q23(b)
60. June 2016 · AS Paper 1 · Q23(c)(i)
Mark scheme June 2016 Paper 1 Q23(c)(i)
61. June 2016 · AS Paper 1 · Q23(c)(ii)
Mark scheme June 2016 Paper 1 Q23(c)(ii)