Q. In a galvanic cell, which electrode undergoes reduction?
A.
Anode
B.
Cathode
C.
Salt bridge
D.
Electrolyte
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Solution
In a galvanic cell, reduction occurs at the cathode.
Correct Answer:
B
— Cathode
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Q. In a redox reaction, which species is reduced?
A.
Oxidizing agent
B.
Reducing agent
C.
Product
D.
Reactant
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Solution
The oxidizing agent is the species that gains electrons and is reduced.
Correct Answer:
A
— Oxidizing agent
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Q. In the reaction 2Ag+ + Zn → 2Ag + Zn2+, which species is oxidized?
A.
Ag+
B.
Zn
C.
Ag
D.
Zn2+
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Solution
Zinc (Zn) is oxidized to Zn2+.
Correct Answer:
B
— Zn
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Q. In the reaction 2Ag+ + Zn → 2Ag + Zn2+, which species is reduced?
A.
Ag+
B.
Zn
C.
Ag
D.
Zn2+
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Solution
Ag+ is reduced as it gains electrons to form Ag.
Correct Answer:
A
— Ag+
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Q. In the reaction 2AgNO3 + Cu → 2Ag + Cu(NO3)2, what is the oxidation state of silver in AgNO3?
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Solution
In AgNO3, silver has an oxidation state of +1.
Correct Answer:
A
— +1
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Q. In the reaction 2Ag^+ + Zn → 2Ag + Zn^2+, what is the oxidation state change for zinc?
A.
0 to +2
B.
+2 to 0
C.
+2 to +1
D.
0 to -1
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Solution
Zinc is oxidized from an oxidation state of 0 to +2.
Correct Answer:
A
— 0 to +2
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Q. In the reaction 2Cr2O7^2- + 14H+ + 6e^- → 4Cr^3+ + 7H2O, what is the role of Cr2O7^2-?
A.
Oxidizing agent
B.
Reducing agent
C.
Neutral agent
D.
None of the above
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Solution
Cr2O7^2- is reduced to Cr^3+, making it the oxidizing agent.
Correct Answer:
A
— Oxidizing agent
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is being oxidized?
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
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Solution
Carbon (C) is being oxidized to carbon dioxide (CO2).
Correct Answer:
B
— C
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is being reduced?
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
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Solution
Fe2O3 is being reduced to Fe as it gains electrons.
Correct Answer:
A
— Fe2O3
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, which element is oxidized?
A.
Iron
B.
Carbon
C.
Oxygen
D.
None
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Solution
Carbon is oxidized as it loses electrons to form CO2.
Correct Answer:
B
— Carbon
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Q. In the reaction 2Fe^3+ + 2I^- → 2Fe^2+ + I2, which species is the reducing agent?
A.
Fe^3+
B.
I^-
C.
Fe^2+
D.
I2
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Solution
I^- donates electrons to Fe^3+, thus it is the reducing agent.
Correct Answer:
B
— I^-
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Q. In the reaction 2H2 + O2 → 2H2O, which element is oxidized?
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Solution
Oxygen (O) is oxidized as it goes from 0 in O2 to -2 in H2O.
Correct Answer:
B
— O
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Q. In the reaction 3H2 + N2 → 2NH3, which element is oxidized?
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Solution
Hydrogen (H) is oxidized as it goes from an oxidation state of 0 to +1 in NH3.
Correct Answer:
A
— H
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Q. In the reaction 4Fe + 3O2 → 2Fe2O3, what is the oxidation state of iron in Fe2O3?
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Solution
In Fe2O3, iron has an oxidation state of +3.
Correct Answer:
B
— +3
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Q. In the reaction Zn + CuSO4 → ZnSO4 + Cu, which element is oxidized?
A.
Zn
B.
Cu
C.
SO4
D.
None of the above
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Solution
Zinc (Zn) is oxidized as it loses electrons to form Zn2+.
Correct Answer:
A
— Zn
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Q. In the redox reaction 2Fe2O3 + 3C → 4Fe + 3CO2, what is the oxidation state of carbon in CO2?
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Solution
In CO2, the oxidation state of carbon is +4.
Correct Answer:
C
— +4
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Q. What is the change in oxidation state of carbon in the reaction: CH4 + 2O2 → CO2 + 2H2O?
A.
0 to +4
B.
+4 to 0
C.
0 to -4
D.
-4 to 0
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Solution
The oxidation state of carbon changes from -4 in CH4 to +4 in CO2.
Correct Answer:
A
— 0 to +4
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Q. What is the oxidation state of chlorine in NaClO3?
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Solution
In NaClO3, chlorine has an oxidation state of +5.
Correct Answer:
C
— +5
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Q. What is the oxidation state of nitrogen in NH4+?
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Solution
In NH4+, nitrogen has an oxidation state of -3.
Correct Answer:
A
— -3
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Q. What is the oxidation state of nitrogen in NO3^-?
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Solution
In NO3^-, nitrogen has an oxidation state of +5.
Correct Answer:
B
— +5
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Q. What is the oxidation state of sulfur in H2SO4?
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Solution
In H2SO4, the oxidation state of sulfur is +6.
Correct Answer:
C
— +6
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Q. What is the product formed when Fe2O3 is reduced by carbon monoxide?
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Solution
The product formed is Fe (iron) when Fe2O3 is reduced by carbon monoxide.
Correct Answer:
A
— Fe
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Q. What is the reducing agent in the reaction 2MnO4- + 5C2O4^2- + 6H+ → 2Mn^2+ + 10CO2 + 3H2O?
A.
MnO4-
B.
C2O4^2-
C.
H+
D.
CO2
Show solution
Solution
C2O4^2- is the reducing agent as it donates electrons.
Correct Answer:
B
— C2O4^2-
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Q. What is the reducing agent in the reaction Zn + CuSO4 → ZnSO4 + Cu?
A.
Zn
B.
Cu
C.
CuSO4
D.
ZnSO4
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Solution
Zinc (Zn) is the reducing agent as it donates electrons to copper.
Correct Answer:
A
— Zn
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Q. What is the reduction half-reaction for the conversion of MnO4- to Mn2+ in acidic medium?
A.
MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
B.
MnO4- + 5e- → Mn2+ + 8H+ + 4H2O
C.
MnO4- + 4H2O + 5e- → Mn2+ + 8H+
D.
MnO4- + 5e- + 4H2O → Mn2+ + 8H+
Show solution
Solution
The correct reduction half-reaction in acidic medium is MnO4- + 8H+ + 5e- → Mn2+ + 4H2O.
Correct Answer:
A
— MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
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Q. What is the reduction half-reaction for the reaction 2MnO4- + 16H+ + 10e- → 2Mn2+ + 8H2O?
A.
MnO4- + 8H2O + 10e- → Mn2+ + 16H+
B.
MnO4- + 10e- + 8H+ → Mn2+ + 4H2O
C.
MnO4- + 10e- → Mn2+ + 8H2O
D.
MnO4- + 16H+ → Mn2+ + 10e- + 8H2O
Show solution
Solution
The correct reduction half-reaction shows the gain of electrons and protons.
Correct Answer:
B
— MnO4- + 10e- + 8H+ → Mn2+ + 4H2O
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Q. What is the reduction half-reaction for the reaction of copper(II) ions with zinc?
A.
Cu^2+ + 2e^- → Cu
B.
Zn → Zn^2+ + 2e^-
C.
Cu → Cu^2+ + 2e^-
D.
Zn^2+ + 2e^- → Zn
Show solution
Solution
The reduction half-reaction is Cu^2+ + 2e^- → Cu.
Correct Answer:
A
— Cu^2+ + 2e^- → Cu
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Q. What is the reduction half-reaction for the reaction of MnO4- in acidic medium?
A.
MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
B.
MnO4- + 3e- → MnO2 + 2H2O
C.
MnO4- + 2e- → MnO2 + 4H+
D.
MnO4- + 4e- + 8H+ → MnO2 + 4H2O
Show solution
Solution
In acidic medium, MnO4- is reduced to Mn2+.
Correct Answer:
A
— MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
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Q. What is the role of a catalyst in a redox reaction?
A.
Increase oxidation
B.
Increase reduction
C.
Speed up the reaction
D.
Change the products
Show solution
Solution
A catalyst speeds up the reaction without being consumed in the process.
Correct Answer:
C
— Speed up the reaction
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Q. Which of the following compounds can act as a reducing agent?
A.
H2O2
B.
Cl2
C.
Na
D.
O2
Show solution
Solution
Sodium (Na) can act as a reducing agent as it readily donates electrons.
Correct Answer:
C
— Na
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Showing 1 to 30 of 40 (2 Pages)
Redox Reactions MCQ & Objective Questions
Redox reactions are a crucial part of chemistry that students must master for their exams. Understanding these reactions not only helps in scoring better but also builds a strong foundation for advanced topics. Practicing MCQs and objective questions on redox reactions is essential for effective exam preparation, as it allows students to familiarize themselves with important questions and enhances their problem-solving skills.
What You Will Practise Here
Definitions of oxidation and reduction
Identifying oxidizing and reducing agents
Balancing redox reactions using half-reaction method
Understanding electrochemical cells and their applications
Key formulas related to redox reactions
Common redox reaction examples in daily life
Diagrams illustrating redox processes
Exam Relevance
Redox reactions are frequently tested in CBSE, State Boards, NEET, and JEE exams. Students can expect questions that require them to balance equations, identify agents, and apply concepts to real-world scenarios. Common question patterns include multiple-choice questions that assess both theoretical understanding and practical application of redox principles.
Common Mistakes Students Make
Confusing oxidation with reduction due to similar terminology
Incorrectly identifying oxidizing and reducing agents
Failing to balance charges and atoms in redox equations
Overlooking the significance of electron transfer in reactions
Misinterpreting the role of electrochemical cells in redox processes
FAQs
Question: What is a redox reaction?Answer: A redox reaction involves the transfer of electrons between two species, resulting in changes in oxidation states.
Question: How can I balance redox reactions?Answer: Redox reactions can be balanced using the half-reaction method, where you separate the oxidation and reduction processes and balance them individually.
Ready to enhance your understanding of redox reactions? Dive into our practice MCQs and test your knowledge to excel in your exams!
