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 641· Oxidation and reduction· JAMB
Find the oxidation number of nitrogen in the ammonium ion, NH₄⁺.
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Answer: B. −3
Explanation and discussion
Question 642· Oxidation and reduction· JAMB
In the reaction 2Mg + O₂ → 2MgO, magnesium is
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Answer: B. oxidised
Explanation and discussion
Question 643· Oxidation and reduction· WAEC
In the reaction 2Mg + O₂ → 2MgO, the reducing agent is
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Answer: A. magnesium
Explanation and discussion
Question 644· Oxidation and reduction· JAMB
Find the oxidation number of manganese in MnO₂.
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Answer: D. +4
Explanation and discussion
Question 645· Oxidation and reduction· JAMB
In the reaction Zn + Cu²⁺ → Zn²⁺ + Cu, zinc is:
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Answer: D. oxidised
Explanation and discussion
Question 646· Rates of chemical reaction· JAMB
Sunlight speeds up the reaction between hydrogen and chlorine because it
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Answer: A. supplies energy to break Cl–Cl bonds
Explanation and discussion
Question 647· Rates of chemical reaction· JAMB
Which of the following reactions is greatly speeded up by light?
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Answer: B. hydrogen and chlorine forming hydrogen chloride
Explanation and discussion
Question 648· Rates of chemical reaction· JAMB
The rate of a reaction is greatest at the start and falls with time because
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Answer: D. the concentration of the reactants decreases
Explanation and discussion
Question 649· Rates of chemical reaction· JAMB
In the energy profile shown, the energy labelled X is the
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Answer: A. activation energy
Explanation and discussion
Question 650· Rates of chemical reaction· JAMB
Photographic film works because silver halides
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Answer: D. decompose when exposed to light
Explanation and discussion
Question 651· Rates of chemical reaction· JAMB
Increasing the concentration of an acid increases its rate of reaction with marble because
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Answer: C. the reacting particles collide more often
Explanation and discussion
Question 652· Rates of chemical reaction· JAMB
Enzymes are
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Answer: D. biological catalysts
Explanation and discussion
Question 653· Rates of chemical reaction· JAMB
A suitable unit for the rate of reaction measured as change in concentration with time is
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Answer: A. mol dm⁻³ s⁻¹
Explanation and discussion
Question 654· Rates of chemical reaction· JAMB
A substance that slows down a chemical reaction is called
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Answer: B. an inhibitor
Explanation and discussion
Question 655· Rates of chemical reaction· WAEC
Which of the following increases the rate of reaction between marble and dilute hydrochloric acid?
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Answer: D. Using powdered marble
Explanation and discussion
Question 656· Rates of chemical reaction· WAEC
Hydrogen peroxide decomposes faster when manganese(IV) oxide is added. The manganese(IV) oxide
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Answer: B. is a catalyst and is unchanged at the end
Explanation and discussion
Question 657· Rates of chemical reaction· WAEC
Powdered marble reacts faster with dilute acid than marble chips of the same mass because the powder
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Answer: C. has a larger surface area
Explanation and discussion
Question 658· Rates of chemical reaction· JAMB
A negative catalyst (inhibitor)
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Answer: C. slows down a reaction
Explanation and discussion
Question 659· Rates of chemical reaction· WAEC
The rate of a reaction can be followed by measuring
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Answer: C. the volume of gas given off over time
Explanation and discussion
Question 660· Rates of chemical reaction· WAEC
For many reactions, a 10 °C rise in temperature roughly
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Answer: A. doubles the rate
Explanation and discussion

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JAMB and WAEC Chemistry questions

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

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

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

Find the oxidation number of manganese in MnO₂.

In the reaction Zn + Cu²⁺ → Zn²⁺ + Cu, zinc is:

Sunlight speeds up the reaction between hydrogen and chlorine because it

Which of the following reactions is greatly speeded up by light?

The rate of a reaction is greatest at the start and falls with time because

In the energy profile shown, the energy labelled X is the

Photographic film works because silver halides

Increasing the concentration of an acid increases its rate of reaction with marble because

Enzymes are

A suitable unit for the rate of reaction measured as change in concentration with time is

A substance that slows down a chemical reaction is called

Which of the following increases the rate of reaction between marble and dilute hydrochloric acid?

Hydrogen peroxide decomposes faster when manganese(IV) oxide is added. The manganese(IV) oxide

Powdered marble reacts faster with dilute acid than marble chips of the same mass because the powder

A negative catalyst (inhibitor)

The rate of a reaction can be followed by measuring

For many reactions, a 10 °C rise in temperature roughly