Lesson 3.1.1

3.1.1 Oxidation numbers Quiz: Pearson Edexcel Chemistry, Unit 3

20 questions

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Lesson 3.1.1, Oxidation numbers: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 3: Redox I, written with Revision Ninja.

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The 20 questions

  1. What is the oxidation number of oxygen in water, H2O?

    • +2
    • -1
    • -2
    • 0

  2. What is the oxidation number of sulfur in the sulfate ion, SO4 2-?

    • -2
    • +4
    • +6
    • +8

  3. What is the oxidation number of oxygen in hydrogen peroxide, H2O2?

    • +1
    • 0
    • -2
    • -1

  4. What is the oxidation number of chromium in the dichromate ion, Cr2O7 2-?

    • +7
    • +12
    • +3
    • +6

  5. What is the oxidation number of manganese in the permanganate ion, MnO4-?

    • +4
    • +8
    • +7
    • +6

  6. What is the oxidation number of hydrogen in the metal hydride NaH?

    • -1
    • +1
    • 0
    • -2

  7. In which species does nitrogen have an oxidation number of -3?

    • NO2
    • NH4+
    • N2O
    • NO3-

  8. Which equation shows a reduction of an element?

    • Fe2+ -> Fe3+ + e-
    • 2I- -> I2 + 2e-
    • Cl2 + 2e- -> 2Cl-
    • Zn -> Zn2+ + 2e-

  9. Oxidation is best defined as which of the following?

    • Loss of protons from the nucleus
    • Gain of electrons and an increase in oxidation number
    • Loss of electrons and an increase in oxidation number
    • Gain of electrons and a decrease in oxidation number

  10. In the reaction Zn + Cu2+ -> Zn2+ + Cu, which species is the reducing agent?

    • Copper(II) ion, Cu2+
    • Copper, Cu
    • Zinc(II) ion, Zn2+
    • Zinc, Zn

  11. Which statement describes a disproportionation reaction?

    • Two different elements exchange places in a compound, with no change in the oxidation number of either one
    • An element in a single species is simultaneously oxidised and reduced
    • A species gains protons from the solvent, which lowers its oxidation number without any electron transfer taking place
    • A species is only oxidised while another species in the same mixture is only reduced at the same time

  12. Which reaction is a disproportionation?

    • Mg + 2HCl -> MgCl2 + H2
    • 2KI + Cl2 -> 2KCl + I2
    • Zn + 2HCl -> ZnCl2 + H2
    • Cl2 + H2O -> HCl + HOCl

  13. Write the oxidation number of nitrogen in NO3- using a Roman numeral.

    • IV
    • III
    • V
    • VII

  14. Which formula has iron in oxidation state +3?

    • Fe2O3
    • FeS
    • FeO
    • FeCl2

  15. Which formula is correct for the compound containing Fe3+ and sulfate ions?

    • Fe3(SO4)2
    • Fe2(SO4)3
    • FeSO4
    • Fe(SO4)3

  16. Why do metals form positive ions in reactions?

    • They gain protons, which adds positive charge
    • They lose neutrons, which leaves a positive charge
    • They gain electrons, which decreases their oxidation numbers
    • They lose electrons, which increases their oxidation numbers

  17. Why do non-metals form negative ions?

    • They lose protons from the nucleus
    • They gain neutrons, which adds negative charge
    • They gain electrons, which decreases their oxidation numbers
    • They lose electrons, which increases their oxidation numbers

  18. Explain why oxidation numbers are useful for classifying reactions.

    • Oxidation numbers show only the mass of each species in the reaction, which is then used to balance the equation
    • Oxidation numbers only classify reactions that involve metals, so reactions of non-metals cannot be classified this way
    • A reaction is redox if oxidation numbers of some elements change, and disproportionation if one element both rises and falls
    • A reaction is redox only if it involves oxygen, because oxygen is the only element whose oxidation number can change

  19. Which species contains an element with oxidation number +2?

    • H2O2
    • Cl-
    • NaH
    • Ca2+

  20. What is the oxidation number of nitrogen in nitric acid, HNO3?

    • -5
    • +1
    • +5
    • +3

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