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

1 hour22 questions
11 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

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    21 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

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    31 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

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    41 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

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    51 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

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    11 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

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      21 mark

      What is the oxidation state of Fe in Fe2O3?

      • +2

      • -2

      • -3

      • +3

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      31 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

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        11 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

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        21 mark

        Extended tier only

        In which reaction is the reactant being reduced?

        • Mg → Mg2+ + 2ē

        • Mg2+ + 2ē → Mg

        • CrO → Cr2O3

        • C → CO2

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