Lesson 4B.1

4B.1 Group 7 trends and halogen reactions Quiz: Pearson Edexcel Chemistry, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4B.1, Group 7 trends and halogen reactions: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 4: Inorganic Chemistry and the Periodic Table, written with Revision Ninja.

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The 20 questions

  1. How do melting temperatures of the halogens change down Group 7?

    • They increase, because the halogens become ionic in character as the group is descended
    • They increase, because larger molecules have stronger London forces
    • They are the same for all halogens, because all of them exist as diatomic molecules at room temperature
    • They decrease, because larger molecules are more reactive and so break apart more readily on heating

  2. How does electronegativity of Group 7 elements change down the group?

    • It increases, because the atoms get larger and so attract the bonding electrons more strongly overall
    • It is the same for all halogens, because they all have seven electrons in their outer shell of the atom
    • It increases, because there are more protons per atom as the group is descended and so attraction rises
    • It decreases, because the bonding pair is further from the nucleus with more shielding

  3. Why does the reactivity of halogens decrease down Group 7?

    • Atoms form weaker bonds with each other further down the group, which makes them less reactive as oxidising agents
    • Atoms gain electrons less easily because they are smaller, so the incoming electron is held more strongly by the nucleus
    • Atoms have higher electronegativity further down the group, which makes them less willing to gain electrons
    • Atoms are larger and harder to reduce, because the incoming electron is further from the nucleus and more shielded

  4. What happens when chlorine water is added to aqueous potassium bromide?

    • A green gas is released
    • The solution turns orange, because bromine is displaced
    • The solution turns colourless, because chlorine is oxidised
    • A white precipitate forms immediately

  5. Which equation shows the displacement of bromide by chlorine?

    • Cl2 + Br- -> ClBr + Cl-
    • Cl2 + 2Br- -> 2Cl- + Br2
    • Cl2 + 2Br- -> 2ClBr
    • Br2 + 2Cl- -> 2Br- + Cl2

  6. What colour is iodine dissolved in an organic solvent such as hexane?

    • Colourless, because the iodine molecules dissolve completely and do not colour the organic solvent at all
    • Violet or purple
    • Green, which is the colour seen when chlorine water is added to an organic solvent in the test
    • Yellow, which is the characteristic colour of bromine dissolved in an organic solvent such as hexane

  7. What is the oxidation number change when chlorine reacts with a Group 1 metal?

    • -1 to 0
    • +1 to 0
    • 0 to -1
    • 0 to +1

  8. Which equation shows the disproportionation of chlorine with water?

    • Cl2 + H2O -> HCl + HOCl
    • Cl2 + 2H2O -> 2HCl + H2O2
    • Cl2 + H2O -> HCl + HClO2
    • Cl2 + H2O -> 2HCl + O2

  9. Which product forms when chlorine reacts with cold, dilute aqueous sodium hydroxide?

    • Sodium hydride, which forms because chlorine reduces the sodium hydroxide to a hydride under these conditions
    • Sodium chlorate(V), NaClO3, which forms when chlorine reacts with cold dilute sodium hydroxide solution
    • Sodium chloride only, because chlorine reacts with cold alkali by simple displacement to form chloride
    • Sodium chlorate(I), NaClO, which is bleach

  10. What is formed by chlorine reacting with hot concentrated sodium hydroxide?

    • Sodium chloride and oxygen
    • Sodium chloride and sodium chlorate(V)
    • Sodium hypochlorite and hydrogen
    • Sodium chloride and sodium chlorate(I) only

  11. Why is chlorine added to drinking water?

    • It forms HOCl, which kills bacteria in water treatment
    • It raises the pH of the water so that it becomes less acidic and more pleasant to drink for the consumer
    • It converts water into hydrogen peroxide, which then destroys all the bacteria in the water supply
    • It removes dissolved metal ions directly from the water by precipitating them out of the solution

  12. Which Group 1 halide with concentrated sulfuric acid gives hydrogen iodide that is further reduced to iodine?

    • Sodium fluoride
    • Sodium chloride
    • Sodium bromide
    • Sodium iodide

  13. What is the order of reducing ability of the hydrogen halides?

    • HBr > HI > HCl
    • HI > HBr > HCl
    • HCl > HBr > HI
    • HF > HCl > HBr

  14. Which precipitate forms when silver nitrate is added to aqueous chloride ions?

    • Yellow silver iodide
    • White silver chloride
    • Cream silver bromide
    • Green silver fluoride

  15. Which silver halide dissolves in dilute aqueous ammonia?

    • Silver chloride
    • Silver iodide
    • Silver fluoride
    • Silver bromide

  16. Which silver halide is insoluble even in concentrated aqueous ammonia?

    • Silver iodide
    • Silver bromide
    • Silver chloride
    • Silver nitrate

  17. What is formed when hydrogen chloride gas reacts with ammonia gas?

    • Nitrogen, which is released as a brown gas when the hydrogen chloride reacts with the ammonia gas
    • Ammonium chloride, which gives white fumes
    • Ammonium hydroxide, which is a colourless solution formed when the two gases dissolve in water together
    • Hydrogen chloride only, because ammonia does not react with the gas and simply mixes with it

  18. Which statement about hydrogen halides dissolved in water is correct?

    • They form alkaline solutions, because the hydrogen halides accept protons from the water they dissolve in
    • They form neutral solutions because they are covalent, so they do not release any hydrogen ions into water
    • They form acidic solutions, with HCl being a strong acid
    • They are all weak acids of the same strength, because they all dissociate only partially in the water

  19. Predict the physical state of astatine at room temperature.

    • Gas
    • Vapour
    • Liquid
    • Solid

  20. Why is fluorine the most reactive halogen?

    • It has the lowest electronegativity of the halogens, so it readily gives up its electrons to other atoms
    • It has the highest melting temperature of the halogens, which reflects its strong bonds and high reactivity
    • It has the largest atomic radius of the halogens, so its outer electrons are the most easily shared with others
    • It has the highest electronegativity and a weak F-F bond that is easily broken

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