JAMB Chemistry questions: Oxidation and reduction

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

1. Question 1· Oxidation and reduction· JAMB

   Which change is a reduction?

   • ANa → Na⁺
   • BFe²⁺ → Fe³⁺
   • CCl⁻ → Cl₂
   • DFe³⁺ → Fe²⁺

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   Explanation and discussion

2. Question 2· Oxidation and reduction· JAMB

   In terms of electron transfer, oxidation is

   • Athe loss of electrons
   • Bthe gain of electrons
   • Cthe gain of hydrogen
   • Dthe loss of oxygen

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3. Question 3· Oxidation and reduction· JAMB

   Find the oxidation number of chromium in K₂Cr₂O₇.

   • A+7
   • B+6
   • C+3
   • D+12

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4. Question 4· Oxidation and reduction· JAMB

   A metal high in the electrochemical series

   • Acannot lose electrons
   • Bis less reactive
   • Cdisplaces metals below it from solutions of their salts
   • Dis a noble metal

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5. Question 5· Oxidation and reduction· JAMB

   In the reaction 2FeCl₂ + Cl₂ → 2FeCl₃, the oxidising agent is

   • AFeCl₃
   • BFeCl₂
   • CCl₂
   • DFe

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6. Question 6· Oxidation and reduction· JAMB

   In the reaction Cl₂ + 2NaOH → NaCl + NaOCl + H₂O, chlorine is

   • Aonly reduced
   • Bonly oxidised
   • Cboth oxidised and reduced
   • Dneither oxidised nor reduced

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7. Question 7· Oxidation and reduction· JAMB

   The oxidation number of manganese in KMnO₄ is:

   • A+2
   • B+4
   • C+6
   • D+7

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8. Question 8· Oxidation and reduction· JAMB

   Find the oxidation number of chlorine in NaClO₃.

   • A−1
   • B+3
   • C+7
   • D+5

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9. Question 9· 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

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10. Question 10· Oxidation and reduction· JAMB

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

    • ACu
    • BCuO
    • CH₂
    • DH₂O

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11. Question 11· Oxidation and reduction· JAMB

    Find the oxidation number of nitrogen in HNO₃.

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

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12. Question 12· 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

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13. Question 13· Oxidation and reduction· JAMB

    Find the oxidation number of sulphur in H₂SO₄.

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

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14. Question 14· 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

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15. Question 15· 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

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16. Question 16· Oxidation and reduction· JAMB

    Find the oxidation number of iron in Fe₂O₃.

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

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    Explanation and discussion

17. Question 17· 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

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18. Question 18· Oxidation and reduction· JAMB

    In 2Na + Cl₂ → 2NaCl, sodium is

    • Aneutralised
    • Breduced
    • Coxidised
    • Dhydrolysed

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19. Question 19· Oxidation and reduction· JAMB

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

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

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20. Question 20· Oxidation and reduction· JAMB

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

    • Areduced
    • Boxidised
    • Ca catalyst
    • Dneutralised

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    Explanation and discussion