Lesson 15B.2

15B.2 Ligand exchange reactions Quiz: Pearson Edexcel Chemistry, Unit 15

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 15B.2, Ligand exchange reactions: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 15: Transition Metals, written with Revision Ninja.

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The 20 questions

  1. What name is given to a reaction where ligands in a complex ion are replaced?

    • Redox reaction
    • Ligand exchange
    • Electrophilic addition
    • Neutralisation

  2. What property of d orbitals changes during ligand exchange to cause a colour change?

    • Hybridisation
    • Energy splitting
    • Electron spin
    • Degeneracy

  3. What is the formula of the precipitate formed when NaOH is added to aqueous copper(II) ions?

    • [Cu(OH)4]2-
    • [Cu(NH3)4]2+
    • [Cu(OH)6]3-
    • Cu(OH)2(H2O)4

  4. Which deep-blue complex ion forms when excess ammonia is added to aqueous copper(II) ions?

    • [Cu(NH3)4]2+
    • [Cu(NH3)6]2+
    • [Cu(NH3)2(H2O)4]2+
    • [Cu(NH3)4(H2O)2]2+

  5. Which complex forms when copper(II) is treated with concentrated chloride ions?

    • Cu(OH)2(H2O)4
    • Copper metal
    • [CuCl4]2-
    • [Cu(NH3)4(H2O)2]2+

  6. What complex ion forms when hexaaquacobalt(II) reacts with concentrated hydrochloric acid?

    • [Co(H2O)4Cl2]
    • [CoCl4]2-
    • [CoCl6]3-
    • [CoCl6]4-

  7. What term describes a metal hydroxide that reacts with both acids and alkalis?

    • Basic
    • Amphiprotic
    • Amphoteric
    • Acidic

  8. How many water ligands are replaced by hydroxide when [Cu(H2O)6]2+ forms the precipitate Cu(OH)2(H2O)4?

    • 4
    • 2
    • 6
    • 1

  9. Which complex ion forms when excess sodium hydroxide is added to chromium(III) hydroxide?

    • [Cr(OH)3(H2O)3]
    • [Cr(OH)6]4-
    • [Cr(OH)6]3-
    • [Cr(OH)4]-

  10. What is the coordination number of copper in the complex ion [Cu(NH3)4(H2O)2]2+?

    • 8
    • 4
    • 2
    • 6

  11. How many chloride ligands replace water in forming [CuCl4]2- from [Cu(H2O)6]2+?

    • Six
    • Two
    • Four
    • Three

  12. What is the coordination number of copper in [CuCl4]2-?

    • 8
    • 2
    • 4
    • 6

  13. Which metal ion gives a hydroxide precipitate with NaOH that dissolves in excess?

    • Fe2+
    • Cr3+
    • Cu2+
    • Co2+

  14. Cu(OH)2 precipitate dissolves in excess aqueous ammonia to form which complex?

    • [Cu(OH)4]2-
    • Cu(NH3)2 precipitate
    • [Cu(NH3)4(H2O)2]2+
    • [CuCl4]2-

  15. Which ligand substitution is accompanied by a colour change from pink to blue?

    • [Cr(H2O)6]3+ to [Cr(NH3)6]3+
    • [Co(H2O)6]2+ to [CoCl4]2-
    • [Fe(H2O)6]2+ to [FeCl6]
    • [Cu(H2O)6]2+ to [Cu(NH3)4(H2O)2]2+

  16. Why is replacing monodentate ligands with bidentate ligands favoured by entropy?

    • Enthalpy becomes negative
    • Decrease in particles
    • Stronger covalent bonds
    • Increase in particles

  17. How many ammonia molecules replace water ligands when forming [Cu(NH3)4(H2O)2]2+?

    • Three
    • Four
    • Six
    • Two

  18. What changes to cause a colour change during a ligand exchange reaction?

    • Metal oxidation state
    • d-orbital energy gap
    • Total electron count
    • Overall ionic charge

  19. What colour change occurs when concentrated chloride ions are added to aqueous cobalt(II) ions?

    • Blue to green
    • Green to yellow
    • Blue to pink
    • Pink to blue

  20. What colour precipitate forms when a little ammonia is added to aqueous copper(II) ions?

    • Deep blue solution
    • Pink precipitate
    • Green precipitate
    • Blue precipitate

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