JAMB and WAEC Chemistry questions: Oxidation and reduction

41 questions with answers and explanations. Tap an option to check yourself.

1. Question 21· Oxidation and reduction· JAMB

   In terms of oxygen, reduction is the

   • Aaddition of oxygen to a substance
   • Bremoval of oxygen from a substance
   • Caddition of electrons only
   • Dloss of hydrogen

   Show answer

   Explanation and discussion

2. Question 22· Oxidation and reduction· JAMB

   In the reaction CuO + H₂ → Cu + H₂O, the reducing agent is

   • ACu
   • BCuO
   • CH₂
   • DH₂O

   Show answer

   Explanation and discussion

3. Question 23· Oxidation and reduction· JAMB

   Find the oxidation number of nitrogen in HNO₃.

   • A+5
   • B+3
   • C+4
   • D−3

   Show answer

   Explanation and discussion

4. Question 24· Oxidation and reduction· WAEC

   Hydrogen sulphide gas is a good

   • Acatalyst
   • Boxidising agent
   • Cdrying agent
   • Dreducing agent

   Show answer

   Explanation and discussion

5. Question 25· Oxidation and reduction· WAEC

   The oxidation number of nitrogen in NH₃ is

   • A+3
   • B−3
   • C0
   • D+5

   Show answer

   Explanation and discussion

6. Question 26· Oxidation and reduction· JAMB

   Hydrogen peroxide can act as

   • Aonly an acid
   • Bboth an oxidising agent and a reducing agent
   • Conly a base
   • Dan inert substance

   Show answer

   Explanation and discussion

7. Question 27· Oxidation and reduction· JAMB

   Find the oxidation number of sulphur in H₂SO₄.

   • A+2
   • B+4
   • C+6
   • D−2

   Show answer

   Explanation and discussion

8. Question 28· Oxidation and reduction· JAMB

   In the reaction H₂S + Cl₂ → 2HCl + S, hydrogen sulphide acts as

   • Aa reducing agent
   • Ban oxidising agent
   • Ca catalyst
   • Dan acid only

   Show answer

   Explanation and discussion

9. Question 29· Oxidation and reduction· WAEC

   In terms of electron transfer, oxidation is the

   • Again of electrons
   • Bloss of electrons
   • Cgain of protons
   • Dloss of neutrons

   Show answer

   Explanation and discussion

10. Question 30· Oxidation and reduction· WAEC

    Oxidation in terms of oxidation number is

    • Ano change in oxidation number
    • Ba decrease in oxidation number
    • Can increase in oxidation number
    • Dthe gain of electrons

    Show answer

    Explanation and discussion

11. Question 31· Oxidation and reduction· JAMB

    Which of the following is a redox reaction?

    • AAgNO₃ + NaCl → AgCl + NaNO₃
    • BNaOH + HCl → NaCl + H₂O
    • CZn + 2HCl → ZnCl₂ + H₂
    • DCaCO₃ → CaO + CO₂

    Show answer

    Explanation and discussion

12. Question 32· Oxidation and reduction· JAMB

    Find the oxidation number of iron in Fe₂O₃.

    • A+6
    • B+2
    • C+3
    • D−3

    Show answer

    Explanation and discussion

13. Question 33· Oxidation and reduction· JAMB

    Iron pipes buried in the ground are protected by attaching blocks of magnesium. This is called

    • Atinning
    • Bgalvanising
    • Celectroplating
    • Dsacrificial protection

    Show answer

    Explanation and discussion

14. Question 34· Oxidation and reduction· JAMB

    In 2Na + Cl₂ → 2NaCl, sodium is

    • Aneutralised
    • Breduced
    • Coxidised
    • Dhydrolysed

    Show answer

    Explanation and discussion

15. Question 35· Oxidation and reduction· WAEC

    An oxidising agent

    • Agains electrons
    • Bloses electrons
    • Cgains protons
    • Ddonates hydrogen

    Show answer

    Explanation and discussion

16. Question 36· Oxidation and reduction· WAEC

    Zinc dust added to blue copper(II) tetraoxosulphate(VI) solution reacts as Zn + Cu²⁺ → Zn²⁺ + Cu. Which species is reduced?

    • Athe copper(II) ion
    • Bzinc metal
    • Cthe zinc ion
    • Dcopper metal

    Show answer

    Explanation and discussion

17. Question 37· Oxidation and reduction· JAMB

    Find the oxidation number of nitrogen in the ammonium ion, NH₄⁺.

    • A+3
    • B−3
    • C+5
    • D+4

    Show answer

    Explanation and discussion

18. Question 38· Oxidation and reduction· JAMB

    In the reaction 2Mg + O₂ → 2MgO, magnesium is

    • Areduced
    • Boxidised
    • Ca catalyst
    • Dneutralised

    Show answer

    Explanation and discussion

19. Question 39· Oxidation and reduction· WAEC

    In the reaction 2Mg + O₂ → 2MgO, the reducing agent is

    • Amagnesium
    • Boxygen
    • Cmagnesium oxide
    • Dnone

    Show answer

    Explanation and discussion

20. Question 40· Oxidation and reduction· JAMB

    Find the oxidation number of manganese in MnO₂.

    • A+6
    • B+2
    • C+7
    • D+4

    Show answer

    Explanation and discussion