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IGCSEScienceCambridge (CIE)Co-ordinated Sciences (Double Award)ChemistryExam Questions6. Chemical ReactionsRedox

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

Exam code: 0654 & 0973

1 hour22 questions

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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

    Choose your answer

    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

    Choose your answer

    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

    Choose your answer

    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

    Choose your answer

    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

    Choose your answer

    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

      Choose your answer

      21 mark

      What is the oxidation state of Fe in Fe2O3?

      • +2

      • -2

      • -3

      • +3

      Choose your answer

      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

        Choose your answer

        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

        Choose your answer

        21 mark

        Extended tier only

        In which reaction is the reactant being reduced?

        • Mg → Mg2+ + 2ē

        • Mg2+ + 2ē → Mg

        • CrO → Cr2O3

        • C → CO2

        Choose your answer