Group 17 — AS & A Level Chemistry (9701) questions by topic
Halogen trends run through this topic: comparing astatine's electronegativity and volatility with iodine's, deducing which reagents oxidise chlorine to a +5 oxidation state, and explaining correct statements about halogen and hydrogen halide properties.
Identify, deduce, explain, state and describe are the leading command words, spread across 34 questions from 2023 to 2025 papers and worth from 1 to 13 marks. With no recorded common mistakes but a strong run of correct answers, this is a topic where instant marking is most useful for confirming a periodic-trend explanation is complete rather than merely plausible, and for catching any slip in deducing an equilibrium concentration from given data.
What examiners look for
- Reports note candidates who deduced an equilibrium concentration of [HI] = 0.85 mol dm-3 tended to gain some credit.
- Strong answers described the difference in composition of the equilibrium mixture at the two given temperatures.
- Candidates who deduced that the forward reaction is endothermic, leading to a lower concentration of H2 and I2 in the equilibrium mixture on cooling, were rewarded.
May–June 2025, Paper 11
Three statements about the halogens, chlorine, bromine and iodine and their compounds are listed. 1 The halogen with the highest boiling point has atoms which form the strongest…
Answer this question and get it marked →Which reagent or reagents and conditions will oxidise chlorine, Cl2, into a compound containing chlorine in the +5 oxidation state? A AgNO3(aq) followed by NH3(aq) at room…
Answer this question and get it marked →May–June 2025, Paper 12
Why do the halogens become less volatile as Group 17 is descended? A The halogen–halogen bond energy decreases. B The halogen–halogen bond energy increases. C The number of…
Answer this question and get it marked →May–June 2025, Paper 13
Mixing aqueous silver nitrate and aqueous sodium chloride produces a precipitate. Addition of which reagent to the mixture gives a colourless solution? A aqueous ammonia B aqueous…
Answer this question and get it marked →Which statement about the properties of halogens and hydrogen halides is correct? A A chloride ion is a stronger reducing agent than an iodide ion. B Chlorine is more volatile…
Answer this question and get it marked →May–June 2025, Paper 14
Which row is correct? A AgI dissolves in aqueous ammonia more readily than AgCl does — AgI reacts with aqueous ammonia B HCl decomposes more readily than HI does — Cl is more…
Answer this question and get it marked →Which anions are formed when chlorine is passed into cold aqueous potassium hydroxide? A Cl^- and ClO^- B Cl^- and ClO3^- C Cl^- and ClO4^- D ClO^- and ClO3^-
Answer this question and get it marked →May–June 2024, Paper 11
A solid sodium halide, NaX, is reacted with concentrated sulfuric acid. The lowest oxidation state of sulfur in the products is +4. Halogen Y2 is less volatile than halogen X2.…
Answer this question and get it marked →Compound Q dissolves in water. Q(aq) does not react with dilute sulfuric acid. Q(aq) forms a precipitate when aqueous silver nitrate is added. This precipitate is partially…
Answer this question and get it marked →May–June 2024, Paper 12
Chlorine gas is reacted with cold aqueous sodium hydroxide. Which statement is correct for this reaction? A Chlorine is both oxidised and reduced. B Chlorine is neither oxidised…
Answer this question and get it marked →The table shows statements about some of the properties of halogens and their compounds and explanations for these properties. Which row shows a correct statement about the…
Answer this question and get it marked →May–June 2024, Paper 13
Which statement is correct? A Hydrogen bromide reduces concentrated sulfuric acid to form sulfur dioxide gas. B Hydrogen bromide decomposes at a higher temperature than hydrogen…
Answer this question and get it marked →ICl is made when Cl2 and I2 react together. Cl2 + I2 <= 2ICl ICl reacts with water. 5ICl + 3H2O - 5HCl + HIO3 + 2I2 Which row is correct? oxidation number of I in ICl reaction…
Answer this question and get it marked →May–June 2024, Paper 21
The elements of Group 17 are called halogens. Complete Table 1.1. Table 1.1 halogen colour at 293 K --- --- chlorine bromine iodine
Answer this question and get it marked →October–November 2024, Paper 11
In reaction 1, concentrated sulfuric acid is added to potassium chloride and the fumes produced are bubbled into aqueous potassium iodide solution. In reaction 2, potassium…
Answer this question and get it marked →The table refers to the hydrogen halides. Which row is correct? oxidation thermal stability --- --- --- A easier to oxidise down the group increases down the group B more…
Answer this question and get it marked →October–November 2024, Paper 12
The colours of the silver halides AgCl, AgBr and AgI differ. The solubilities of these halides in aqueous ammonia also differ. Which row is correct? colour of AgBr silver halide…
Answer this question and get it marked →The name 'chlorate' is used for an anion consisting of chlorine and oxygen only. In a molecule of ICl, the iodine atom has oxidation number x and the chlorine atom has oxidation…
Answer this question and get it marked →October–November 2024, Paper 13
In reaction 1, concentrated sulfuric acid is added to potassium chloride and the fumes produced are bubbled into aqueous potassium iodide solution. In reaction 2, potassium…
Answer this question and get it marked →The table refers to the hydrogen halides. Which row is correct? oxidation thermal stability --- --- --- A easier to oxidise down the group increases down the group B more…
Answer this question and get it marked →October–November 2024, Paper 21
Chlorine is one of the elements in Group 17 of the Periodic Table. Describe the colours of the Group 17 elements, chlorine to iodine, at room temperature.
Answer this question and get it marked →October–November 2024, Paper 23
Chlorine is one of the elements in Group 17 of the Periodic Table. Describe the colours of the Group 17 elements, chlorine to iodine, at room temperature.
Answer this question and get it marked →February–March 2023, Paper 12
Powder P is a mixture containing two of AgCl, AgBr or AgI. P is shaken with dilute aqueous ammonia. A yellow solid, Q, remains. The mixture is filtered and Q is washed and dried.…
Answer this question and get it marked →May–June 2023, Paper 11
Bromine reacts with aqueous sodium hydroxide at 25 °C. reaction 1: Br2(aq) + 2NaOH(aq) → NaBr(aq) + NaOBr(aq) + H2O(l) The NaOBr formed is unstable at 25 °C and reacts further.…
Answer this question and get it marked →May–June 2023, Paper 13
Which row shows the expected properties of the element astatine when compared to the properties of the element iodine? electronegativity of astatine compared to iodine volatility…
Answer this question and get it marked →Which statement about the halogens is correct? A Iodine cannot behave as an oxidising agent. B The volatility of the elements increases from chlorine to iodine because of the…
Answer this question and get it marked →When concentrated sulfuric acid is added to solid sodium bromide, bromine gas is produced, along with a number of other products. However, when concentrated sulfuric acid is added…
Answer this question and get it marked →May–June 2023, Paper 23
Hydrogen chloride gas is made in the laboratory by adding concentrated sulfuric acid to potassium chloride. Construct an equation for this reaction.
Answer this question and get it marked →October–November 2023, Paper 11
In this question, Q represents an atom of chlorine, bromine or iodine. Which explanation for the variation in volatility down Group 17 is correct? A: Instantaneous dipole-induced…
Answer this question and get it marked →Which statement about the halogens or halide ions is correct? A: Bromide ions react to form a white precipitate when added to silver nitrate solution. B: Bromine does not oxidise…
Answer this question and get it marked →October–November 2023, Paper 12
Chlorine reacts with sodium bromide: 1/2Cl2 + NaBr - NaCl + 1/2Br2. Which words correctly describe this reaction? 1 redox; 2 displacement; 3 disproportionation. A: 1, 2 and 3. B:…
Answer this question and get it marked →Iodine has a higher melting point than chlorine. What is the reason for this? A: Iodine has stronger covalent bonds than chlorine. B: Iodine molecules have stronger permanent…
Answer this question and get it marked →October–November 2023, Paper 13
In this question, Q represents an atom of chlorine, bromine or iodine. Which explanation for the variation in volatility down Group 17 is correct? A Instantaneous dipole-induced…
Answer this question and get it marked →Which statement about the halogens or halide ions is correct? A Bromide ions react to form a white precipitate when added to silver nitrate solution. B Bromine does not oxidise…
Answer this question and get it marked →Other AS & A Level Chemistry topics
- Practical skills (106)
- Hydrocarbons (65)
- Chemical bonding (63)
- The Periodic Table: chemical periodicity (59)
- Chemical energetics (53)
- Equilibria (53)
- Introduction to organic chemistry (53)
- Reaction kinetics (52)
- Carboxylic acids and derivatives (52)
- Group 2 (51)
- Carbonyl compounds (45)
- Atomic structure (44)