JAMB and WAEC Chemistry questions

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

All topics Acids, bases and salts · 58 Air · 37 Atomic structure and bonding · 59 Chemical combination · 58 Chemical equilibrium · 37 Chemistry and industry · 35 Electrolysis · 41 Energy changes · 38 Environmental pollution · 32 Kinetic theory of matter and gas laws · 45 Metals and their compounds · 47 Non-metals and their compounds · 45 Organic compounds · 72 Oxidation and reduction · 41 Rates of chemical reaction · 38 Separation of mixtures and purification · 42 Solubility · 36 Water · 39

Question 621· Oxidation and reduction· JAMB
The oxidation number of manganese in KMnO₄ is:
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Answer: D. +7
Explanation and discussion
Question 622· Oxidation and reduction· JAMB
Find the oxidation number of chlorine in NaClO₃.
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Answer: D. +5
Explanation and discussion
Question 623· Oxidation and reduction· WAEC
In the change Fe²⁺ → Fe³⁺ + e⁻, the iron(II) ion is
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Answer: B. oxidised
Explanation and discussion
Question 624· Oxidation and reduction· WAEC
Find the oxidation number of manganese in KMnO₄.
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Answer: B. +7
Explanation and discussion
Question 625· Oxidation and reduction· JAMB
In terms of oxygen, reduction is the
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Answer: B. removal of oxygen from a substance
Explanation and discussion
Question 626· Oxidation and reduction· JAMB
In the reaction CuO + H₂ → Cu + H₂O, the reducing agent is
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Answer: C. H₂
Explanation and discussion
Question 627· Oxidation and reduction· JAMB
Find the oxidation number of nitrogen in HNO₃.
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Answer: A. +5
Explanation and discussion
Question 628· Oxidation and reduction· WAEC
Hydrogen sulphide gas is a good
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Answer: D. reducing agent
Explanation and discussion
Question 629· Oxidation and reduction· WAEC
The oxidation number of nitrogen in NH₃ is
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Answer: B. −3
Explanation and discussion
Question 630· Oxidation and reduction· JAMB
Hydrogen peroxide can act as
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Answer: B. both an oxidising agent and a reducing agent
Explanation and discussion
Question 631· Oxidation and reduction· JAMB
Find the oxidation number of sulphur in H₂SO₄.
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Answer: C. +6
Explanation and discussion
Question 632· Oxidation and reduction· JAMB
In the reaction H₂S + Cl₂ → 2HCl + S, hydrogen sulphide acts as
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Answer: A. a reducing agent
Explanation and discussion
Question 633· Oxidation and reduction· WAEC
In terms of electron transfer, oxidation is the
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Answer: B. loss of electrons
Explanation and discussion
Question 634· Oxidation and reduction· WAEC
Oxidation in terms of oxidation number is
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Answer: C. an increase in oxidation number
Explanation and discussion
Question 635· Oxidation and reduction· JAMB
Which of the following is a redox reaction?
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Answer: C. Zn + 2HCl → ZnCl₂ + H₂
Explanation and discussion
Question 636· Oxidation and reduction· JAMB
Find the oxidation number of iron in Fe₂O₃.
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Answer: C. +3
Explanation and discussion
Question 637· Oxidation and reduction· JAMB
Iron pipes buried in the ground are protected by attaching blocks of magnesium. This is called
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Answer: D. sacrificial protection
Explanation and discussion
Question 638· Oxidation and reduction· JAMB
In 2Na + Cl₂ → 2NaCl, sodium is
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Answer: C. oxidised
Explanation and discussion
Question 639· Oxidation and reduction· WAEC
An oxidising agent
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Answer: A. gains electrons
Explanation and discussion
Question 640· Oxidation and reduction· WAEC
Zinc dust added to blue copper(II) tetraoxosulphate(VI) solution reacts as Zn + Cu²⁺ → Zn²⁺ + Cu. Which species is reduced?
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Answer: A. the copper(II) ion
Explanation and discussion

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JAMB and WAEC Chemistry questions

The oxidation number of manganese in KMnO₄ is:

Find the oxidation number of chlorine in NaClO₃.

In the change Fe²⁺ → Fe³⁺ + e⁻, the iron(II) ion is

Find the oxidation number of manganese in KMnO₄.

In terms of oxygen, reduction is the

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

Find the oxidation number of nitrogen in HNO₃.

Hydrogen sulphide gas is a good

The oxidation number of nitrogen in NH₃ is

Hydrogen peroxide can act as

Find the oxidation number of sulphur in H₂SO₄.

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

In terms of electron transfer, oxidation is the

Oxidation in terms of oxidation number is

Which of the following is a redox reaction?

Find the oxidation number of iron in Fe₂O₃.

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

In 2Na + Cl₂ → 2NaCl, sodium is

An oxidising agent

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