Lesson 3.1.3

3.1.3 The halogens Quiz: OCR Chemistry, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.3, The halogens: 20 multiple choice questions for the OCR Chemistry (H432), Unit 2: Periodic table and energy, written with Revision Ninja.

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The 20 questions

  1. How many electron pairs are shared between two atoms in a halogen molecule?

    • Two pairs
    • Three pairs
    • One pair
    • Four pairs

  2. What is the outer electron configuration of the halogens?

    • s2 p6
    • s1 p5
    • s2 p3
    • s2 p5

  3. Why do the boiling points of halogens increase down Group 17?

    • Stronger London forces
    • Weaker dipole forces
    • Stronger hydrogen bonds
    • Stronger covalent bonds

  4. Which order of reactivity is correct for chlorine, bromine and iodine as oxidising agents?

    • Cl2 = Br2 = I2
    • Cl2 > Br2 > I2
    • Br2 > Cl2 > I2
    • I2 > Br2 > Cl2

  5. What colour solution forms when chlorine water is added to aqueous bromide ions?

    • Orange
    • Purple
    • Pale green
    • Colourless

  6. Why does reactivity decrease down Group 17?

    • Higher electronegativity
    • Decreased shielding
    • Increased nuclear attraction
    • Increased atomic radius

  7. Which ionic equation represents the displacement reaction between chlorine water and aqueous iodide ions?

    • 2Cl- + I2 → Cl2 + 2I-
    • Cl2 + 2I- → 2Cl- + I2
    • Cl2 + I- → Cl- + I2
    • Cl- + 2I- → Cl2 + I2

  8. What products form when chlorine reacts with cold, dilute sodium hydroxide?

    • NaCl, NaClO and H2O
    • NaCl and NaClO only
    • NaClO3 and HCl
    • NaCl, NaClO3 and H2O

  9. What happens to chlorine during its disproportionation reaction with water?

    • Only reduced
    • Hydrated and precipitated
    • Oxidised and reduced
    • Only oxidised

  10. What is the primary benefit of adding chlorine to drinking water supplies?

    • Kills harmful bacteria
    • Prevents tooth decay
    • Removes dissolved nitrates
    • Lowers water pH

  11. What physical state is fluorine at room temperature and pressure?

    • Gas
    • Solid
    • Liquid
    • Aqueous

  12. What colour is the silver halide precipitate formed from bromide ions and aqueous silver ions?

    • Yellow
    • White
    • Cream
    • Black

  13. What colour is the precipitate formed when aqueous silver ions react with iodide ions?

    • Yellow
    • Cream
    • White
    • Brown

  14. Which reagent is required to dissolve a precipitate of silver bromide?

    • Aqueous sodium hydroxide
    • Concentrated aqueous ammonia
    • Dilute aqueous ammonia
    • Dilute nitric acid

  15. What is the percentage by mass of chlorine in NaCl? (Na = 23.0, Cl = 35.5)

    • 50.0%
    • 71.0%
    • 39.3%
    • 60.7%

  16. How many moles of NaOH are needed to react completely with 1 mol of Cl2 in cold dilute solution?

    • 4 mol
    • 1 mol
    • 2 mol
    • 0.5 mol

  17. In Cl2 + 2Br- → 2Cl- + Br2, which species is oxidised?

    • Cl- ions
    • Br2
    • Br- ions
    • Cl2

  18. Why does the reactivity of halogens decrease down Group 17 as atomic number increases?

    • Decreased atomic radius
    • Increased electron shielding
    • Decreased electron shielding
    • Increased nuclear attraction

  19. What is the oxidation number of chlorine in sodium chlorate(I), NaClO?

    • +1
    • +3
    • +5
    • -1

  20. What hazard is associated with reacting chlorine with organic matter in water?

    • Chlorinated hydrocarbons produced
    • Radioactive isotopes formed
    • Insoluble precipitates formed
    • Toxic oxygen gas

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