Oxidation and Reduction Practice Questions
WAEC (West Africa) · WAEC Chemistry · 139 free MCQs with instant results and detailed explanations.
139
Total
40
Easy
69
Medium
30
Hard
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Sample Questions from Oxidation and Reduction
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Q1
Easy
Which of the following statements correctly describes an oxidation reaction?
A.
It involves the loss of electrons.
B.
It involves the gain of protons.
C.
It involves the gain of neutrons.
D.
It involves the loss of protons.
Show Answer & Explanation
Correct Answer: A
Oxidation is defined as the process where an atom, ion, or molecule loses electrons. Therefore, option A is the correct description of oxidation.
Q2
Easy
In a chemical reaction, if substance A is oxidized and substance B is reduced, which of the following is true?
A.
A gains electrons and B loses electrons.
B.
A loses electrons and B gains electrons.
C.
Both A and B are oxidized.
D.
Both A and B are reduced.
Show Answer & Explanation
Correct Answer: B
Oxidation involves the loss of electrons, which occurs with substance A, while reduction involves the gain of electrons, which occurs with substance B. Therefore, A loses electrons and B gains electrons.
Q3
Easy
Which of the following species is reduced in the reaction: Cu^2+ + 2e^- → Cu?
A.
Cu
B.
Cu^2+
C.
e^-
D.
None of the above
Show Answer & Explanation
Correct Answer: B
In the given reaction, Cu^2+ gains two electrons to form Cu, which means Cu^2+ is being reduced (gaining electrons). Hence, option B is the correct answer.
Q4
Medium
Which of the following statements defines oxidation in terms of electron transfer?
A.
Oxidation is the gain of electrons.
B.
Oxidation is the loss of electrons.
C.
Oxidation is the combination with oxygen.
D.
Oxidation is the removal of hydrogen.
Show Answer & Explanation
Correct Answer: B
Oxidation is defined as the process in which an atom, ion, or molecule loses electrons, resulting in an increase in oxidation state.
Q5
Medium
In a redox reaction, which of the following species is reduced?
A.
Fe^3+ + 3e^- → Fe
B.
Cu → Cu^2+ + 2e^-
C.
Zn → Zn^2+ + 2e^-
D.
Cl2 + 2e^- → 2Cl^-
Show Answer & Explanation
Correct Answer: A
Reduction is defined as the gain of electrons. In option A, Fe^3+ gains 3 electrons to become Fe, indicating it is reduced.
Q6
Medium
Which of the following pairs represents a redox reaction?
A.
2Na + Cl2 → 2NaCl
B.
H2 + O2 → H2O
C.
Ca + 2H2O → Ca(OH)2 + H2
D.
C + O2 → CO2
Show Answer & Explanation
Correct Answer: A
In the reaction 2Na + Cl2 → 2NaCl, sodium (Na) is oxidized (loses electrons) and chlorine (Cl2) is reduced (gains electrons), confirming it as a redox reaction.
Q7
Medium
When zinc reacts with copper(II) sulfate, which of the following changes occurs?
A.
Zinc is oxidized and copper is reduced.
B.
Copper is oxidized and zinc is reduced.
C.
Both zinc and copper are oxidized.
D.
No redox change occurs.
Show Answer & Explanation
Correct Answer: A
Zinc donates electrons to copper(II) ions in the reaction, meaning zinc is oxidized and copper(II) ions are reduced to copper metal.
Q8
Hard
Which of the following statements correctly describes the redox reaction in the process of electrolysis of water?
A.
Oxygen is formed at the anode while hydrogen is formed at the cathode.
B.
Both oxygen and hydrogen are formed at the anode.
C.
Hydrogen is formed at the anode while oxygen is formed at the cathode.
D.
No gas is produced at either electrode.
Show Answer & Explanation
Correct Answer: A
In the electrolysis of water, water is decomposed into oxygen and hydrogen gases. Oxygen is produced at the anode (positive electrode) and hydrogen is produced at the cathode (negative electrode), making option A the correct statement.
Q9
Hard
In a redox reaction, if the oxidation state of an element changes from +3 to +5, what type of process is occurring?
A.
Reduction
B.
Oxidation
C.
Neither reduction nor oxidation
D.
Both reduction and oxidation
Show Answer & Explanation
Correct Answer: B
The increase in oxidation state from +3 to +5 indicates that the element is losing electrons. This loss of electrons corresponds to oxidation, so option B is the correct answer.
Q10
Hard
Which of the following statements correctly describes an oxidation reaction?
A.
It involves the loss of electrons.
B.
It involves the gain of hydrogen atoms.
C.
It involves the reduction of a substance.
D.
It involves the gain of electrons.
Show Answer & Explanation
Correct Answer: A
An oxidation reaction involves the loss of electrons from a substance. This is a fundamental principle in redox reactions where one species loses electrons (is oxidized), while another gains them (is reduced).
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Oxidation and Reduction — WAEC (West Africa) WAEC Chemistry Practice Questions Online
This page contains 139 practice MCQs for the chapter Oxidation and Reduction in WAEC (West Africa) WAEC Chemistry. The questions are organized by difficulty — 40 easy, 69 medium, 30 hard — so you can choose the right level for your preparation.
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