Redox (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Chemistry): Exam Questions

Exam code: 0654 & 0973

1 hour24 questions
1
1 mark

Extended tier only

Which row correctly describes oxidation in terms of oxygen, electrons and oxidation state?

 

oxygen is

electrons are

oxidation state is

A

added

added

increased

B

added

lost

increased

C

lost

added

decreased

D

lost

lost

decreased

    2
    1 mark

    Magnesium reacts with iron(III) oxide in the following reaction.

    magnesium + iron(III) oxide → magnesium oxide + iron

    Which statement about this reaction is correct?

    • Magnesium oxide is reduced

    • Iron is oxidised

    • Magnesium is oxidised

    • Iron(III) oxide is oxidised

    3
    1 mark

    When copper is heated in air, its surface turns black.

    What is happening to the copper in this reaction?

    • Copper undergoes thermal decomposition

    • Copper is oxidised

    • Copper burns with a lilac flame

    • Copper is reduced

    4
    1 mark

    Lead(II) oxide undergoes a number of different redox reactions.

    In which of the following reactions is lead(II) oxide, PbO, not reduced?

    • PbO + Zn → Pb + ZnO

    • PbO + H2 → Pb + H2O

    • PbO + C → Pb + CO

    • 2PbO + O2 → 2PbO2

    5
    1 mark

    The following equations are all examples of redox reactions.

    In which equation is the underlined substance being oxidised?

    • CO2 + C → 2CO

    • FeO + Mg → MgO + Fe

    • 3CO + Fe2O3 → 2Fe + 3CO2

    • CuCO3 → CuO + CO2

    1
    1 mark

    Three reactions are shown below.

    NO + O3 → NO2 + O2

    2C + O2 → 2CO

    2MgO + O2 → 2MgO2

    Which row correctly describes the process each reactant molecule undergoes?

     

    NO

    O3

    MgO

    A

    oxidised

    reduced

    oxidised

    B

    oxidised

    oxidised

    reduced

    C

    reduced

    oxidised

    oxidised

    D

    reduced

    reduced

    oxidised

      2
      1 mark

      What is the oxidation state of Fe in Fe2O3?

      • +2

      • -2

      • -3

      • +3

      3
      1 mark

      Extended tier only

      Which row correctly describes the process of reduction in terms of oxygen, electrons and oxidation state?

       

      oxygen is

      electrons are

      oxidation state is

      A

      lost

      added

      unchanged

      B

      added

      lost

      increased

      C

      lost

      added

      decreased

      D

      added

      lost

      unchanged

        4
        1 mark

        Copper(II) oxide reacts with hydrogen gas.

        CuO (s) + H2 (g) → Cu (s) + H2O (l)

        Which substance is reduced?

        • CuO

        • H2

        • Cu

        • H2O

        5
        1 mark

        Aqueous copper(II) sulfate reacts with zinc according to the equation shown.

        Zn (s) + CuSO4​ (aq) → ZnSO4​ (aq) + Cu (s)

        Which row correctly identifies the oxidising agent and the reducing agent in this reaction?

        oxidising agent

        reducing agent

        A

        CuSO4

        Zn

        B

        Zn

        CuSO4

        C

        Cu

        ZnSO4

        D

        ZnSO4

        Cu

          1
          1 mark

          A series of redox reactions are shown. What is the oxide that undergoes oxidation?

          1

          2CO + 2NO → 2CO2 + N2

          2

          Fe2O3 + 2Al → Al2O3 + 2Fe

          3

          2ZnO + C → 2Zn + CO2

          4

          Fe2O3 + 3CO → 2Fe + 3CO2

          • CO

          • C

          • NO

          • Fe2O3

          2
          1 mark

          Extended tier only

          In which reaction is the reactant being reduced?

          • Mg → Mg2+ + 2ē

          • Mg2+ + 2ē → Mg

          • CrO → Cr2O3

          • C → CO2