Lesson 3.2.5.6

3.2.5.6 Catalysts Quiz: AQA Chemistry, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.2.5.6, Catalysts: 20 multiple choice questions for the AQA Chemistry (7405), Unit 2: Inorganic chemistry, written with Revision Ninja.

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The 20 questions

  1. What is a heterogeneous catalyst?

    • A catalyst that is always a solid metal oxide only
    • A catalyst in the same phase as the reactants
    • A catalyst in a different phase from the reactants
    • A catalyst that is consumed completely in the reaction

  2. What is a homogeneous catalyst?

    • A catalyst made of enzymes only
    • A catalyst in the same phase as the reactants
    • A catalyst that stops the reaction
    • A catalyst in a different phase from the reactants

  3. Where does a heterogeneous catalyst reaction take place?

    • Throughout the bulk of the gas phase
    • At the bottom of the reaction vessel
    • Inside the reactant molecules only
    • At active sites on the surface of the catalyst

  4. Why is a support medium used with a heterogeneous catalyst?

    • To maximise the surface area of the catalyst and minimise its cost
    • To change the phase of the reactants
    • To increase the temperature of the reaction
    • To make the catalyst dissolve in the reactants

  5. Which catalyst is used in the Contact process?

    • Mn2+
    • Fe
    • Pt only
    • V2O5

  6. Which catalyst is used as a heterogeneous catalyst in the Haber process?

    • Copper(II) ions
    • Vanadium(V) oxide
    • Manganese(II) ions
    • Iron

  7. How does a heterogeneous catalyst become less efficient over time?

    • It is oxidised to a gas
    • It increases in mass by absorbing reactants
    • Impurities block its active sites by poisoning
    • Its phase changes to a liquid

  8. Which equation shows the first step in the Contact process catalysed by V2O5?

    • 2SO2 + 2H2O -> 2H2SO3
    • SO2 + O2 -> SO3 only
    • V2O5 + H2O -> H2V2O6
    • SO2 + V2O5 -> SO3 + V2O4

  9. Which equation shows the regeneration of the V2O5 catalyst in the Contact process?

    • 2V2O5 + O2 -> 4VO2
    • V2O4 + 1/2 O2 -> V2O5
    • V2O5 -> V2O4 + O2
    • V2O4 + SO2 -> V2O5 + S

  10. In the reaction between I- and S2O8^2-, Fe2+ ions act as a catalyst. Which step is correct for the catalytic cycle?

    • 2Fe3+ + S2O8^2- -> 2Fe2+ + 2SO4^2-
    • 2Fe2+ + S2O8^2- -> 2Fe3+ + 2SO4^2-
    • Fe2+ + SO4^2- -> FeSO4 only
    • Fe2+ + I- -> FeI2 only

  11. In the Fe2+ catalysed reaction of I- with S2O8^2-, what is the second step of the catalytic cycle?

    • Fe2+ + I2 -> FeI2 + e-
    • 2Fe3+ + 2I- -> 2Fe2+ + I2
    • I- + Fe3+ -> I2 + Fe only
    • 2Fe3+ + SO4^2- -> Fe2(SO4)3

  12. Why is the Fe2+ catalysed reaction between I- and S2O8^2- slow without the catalyst?

    • The reaction needs light to start
    • The reaction is endothermic with no energy change
    • The two negative ions repel each other, giving a high activation energy
    • Iodide ions are not oxidised by any species

  13. Which feature explains why transition metals are good catalysts?

    • They dissolve only in organic solvents
    • They are always gases at room temperature
    • They can change oxidation state, which allows them to take part in electron transfer
    • They always contain a full d sub-level

  14. What is an autocatalyst?

    • A catalyst that is added at the start of every reaction
    • A catalyst that stops the reaction once a product forms
    • A product of the reaction that catalyses the reaction it is formed in
    • A catalyst that is a gas at all temperatures

  15. Which ion autocatalyses the reaction between ethanedioate and acidified manganate(VII)?

    • Cl-
    • Mn2+
    • Na+
    • SO4^2-

  16. Why does the reaction between ethanedioate and manganate(VII) start slowly?

    • Ethanedioate does not react with acid at all
    • No Mn2+ is present initially, so the autocatalysis has not yet started
    • The manganate(VII) is colourless at the start
    • The reaction is endothermic and needs heating always

  17. Which property of transition metals is important for catalysis in the Haber process using iron?

    • Forming only colourless compounds
    • Ability to form only ionic compounds
    • Variable oxidation states that allow adsorption and release of reactants
    • High solubility in water at all times

  18. Which statement about homogeneous catalysts is correct?

    • They increase the equilibrium constant of every reaction
    • They are always solids and reactants are always gases
    • They form an intermediate species with the reactants in the same phase
    • They are always removed from the reaction mixture

  19. Explain why variable oxidation states are important for transition metal catalysts.

    • They ensure the catalyst is always in its highest oxidation state
    • They make the catalyst unreactive so it is not consumed
    • They stop the reaction from reaching equilibrium
    • They allow the catalyst to accept electrons from one reactant and donate them to another, forming intermediates

  20. Explain why a catalyst does not change the position of an equilibrium.

    • It changes the enthalpy change of the reaction
    • It increases the forward reaction only
    • It removes products from the equilibrium mixture
    • It speeds up the forward and backward reactions equally, so equilibrium is reached faster but the position is unchanged

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