REDOX REACTIONS QUIZ (OBJECTIVE QUESTIONS)
Redox reactions are chemical reactions that involve the transfer of electrons between substances. They are fundamental in processes like respiration, corrosion, batteries, and industrial reactions. This quiz tests your understanding of oxidation, reduction, and electron flow.
Score yourself over 20 at the end with answers and explanation.
Redox Reactions Quiz
1. Redox reactions involve the transfer of
A. Protons
B. Neutrons
C. Electrons
D. Heat
2. Oxidation is defined as
A. Gain of electrons
B. Loss of electrons
C. Gain of protons
D. Loss of neutrons
3. Reduction is defined as
A. Gain of electrons
B. Loss of electrons
C. Gain of protons
D. Loss of neutrons
4. In the reaction 2Mg + O₂ → 2MgO, magnesium is
A. Oxidized
B. Reduced
C. Neither
D. Both
5. In the same reaction, oxygen is
A. Oxidized
B. Reduced
C. Neither
D. Both
Redox Reactions Quiz
6. A substance that loses electrons is called a
A. Oxidizing agent
B. Reducing agent
C. Neutral agent
D. Catalyst
7. A substance that gains electrons is called a
A. Oxidizing agent
B. Reducing agent
C. Neutral agent
D. Catalyst
8. In Fe₂O₃ + 3CO → 2Fe + 3CO₂, CO acts as
A. Oxidizing agent
B. Reducing agent
C. Neutral agent
D. Precipitant
9. In the same reaction, Fe₂O₃ acts as
A. Oxidizing agent
B. Reducing agent
C. Neutral agent
D. Precipitant
10. Oxidation numbers help to
A. Measure pH
B. Identify electron transfer
C. Calculate mass
D. Determine boiling point
Redox Reactions Quiz
11. In H₂ + Cl₂ → 2HCl, hydrogen is
A. Oxidized
B. Reduced
C. Neither
D. Both
12. In the same reaction, chlorine is
A. Oxidized
B. Reduced
C. Neither
D. Both
13. Displacement reactions are often
A. Redox reactions
B. Neutralization reactions
C. Precipitation reactions
D. Endothermic reactions
14. Rusting of iron is an example of
A. Combustion
B. Redox reaction
C. Neutralization
D. Precipitation
15. Batteries operate on
A. Neutralization
B. Redox reactions
C. Combustion
D. Decomposition
Redox Reactions Quiz
16. Electrolysis involves
A. Only oxidation
B. Only reduction
C. Both oxidation and reduction
D. No electron transfer
17. Oxidizing agents are
A. Electron donors
B. Electron acceptors
C. Neutral substances
D. Metals only
18. Reducing agents are
A. Electron donors
B. Electron acceptors
C. Nonmetals only
D. Catalysts
19. In 2K + Cl₂ → 2KCl, potassium is
A. Oxidized
B. Reduced
C. Neither
D. Both
20. In the same reaction, chlorine is
A. Oxidized
B. Reduced
C. Neither
D. Both
Redox Reactions Quiz ANSWERS AND EXPLANATIONS
1. C – Redox reactions involve the transfer of electrons from one species to another, changing oxidation states.
2. B – Oxidation is the loss of electrons, increasing the oxidation number of the element.
3. A – Reduction is the gain of electrons, decreasing the oxidation number of the element.
4. A – Magnesium loses 2 electrons per atom and is oxidized to Mg²⁺.
5. B – Oxygen gains 2 electrons per atom and is reduced to O²⁻.
6. B – A substance that loses electrons donates them and is a reducing agent.
7. A – A substance that gains electrons accepts them and is an oxidizing agent.
8. B – CO loses electrons to Fe₂O₃, acting as a reducing agent.
9. A – Fe₂O₃ gains electrons and is the oxidizing agent in the reaction.
10. B – Oxidation numbers track electron transfer in chemical reactions.
11. A – Hydrogen loses electrons to chlorine, so it is oxidized.
12. B – Chlorine gains electrons from hydrogen, so it is reduced.
13. A – Single displacement reactions often involve one element being oxidized and another reduced.
14. B – Rusting involves iron oxidizing in the presence of oxygen and water, a slow redox process.
15. B – Batteries generate electricity through controlled redox reactions between electrodes.
16. C – Electrolysis separates compounds via both oxidation at the anode and reduction at the cathode.
17. B – Oxidizing agents accept electrons, causing other substances to be oxidized.
18. A – Reducing agents donate electrons, causing other substances to be reduced.
19. A – Potassium loses one electron per atom to chlorine and is oxidized.
20. B – Chlorine gains one electron per atom from potassium and is reduced.
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