Q. In a redox reaction, if the oxidation number of an element increases, what happens to that element? (2020)
A.
It is oxidized
B.
It is reduced
C.
It remains unchanged
D.
It forms a compound
Show solution
Solution
An increase in oxidation number indicates that the element is losing electrons, which means it is being oxidized.
Correct Answer:
A
— It is oxidized
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Q. In a redox reaction, if the oxidation state of an element decreases, what happens to that element? (2021)
A.
It is oxidized
B.
It is reduced
C.
It remains unchanged
D.
It is ionized
Show solution
Solution
A decrease in oxidation state indicates that the element has gained electrons, which means it is reduced.
Correct Answer:
B
— It is reduced
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Q. In a redox reaction, if the oxidation state of an element decreases, what has occurred? (2021)
A.
Oxidation
B.
Reduction
C.
Neutralization
D.
Decomposition
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Solution
A decrease in oxidation state indicates that the element has gained electrons, which is defined as reduction.
Correct Answer:
B
— Reduction
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Q. In a redox reaction, if the oxidation state of an element decreases, what is happening to that element? (2021)
A.
It is being oxidized
B.
It is being reduced
C.
It is unchanged
D.
It is ionized
Show solution
Solution
A decrease in oxidation state indicates that the element is gaining electrons, which means it is being reduced.
Correct Answer:
B
— It is being reduced
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Q. In a redox reaction, if the oxidation state of an element decreases, what is it undergoing? (2021)
A.
Oxidation
B.
Reduction
C.
Neutralization
D.
Decomposition
Show solution
Solution
If the oxidation state of an element decreases, it is gaining electrons, which is known as reduction.
Correct Answer:
B
— Reduction
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Q. In a redox reaction, if the oxidation state of an element increases, what happens to that element? (2021)
A.
It is oxidized
B.
It is reduced
C.
It remains unchanged
D.
It forms a compound
Show solution
Solution
An increase in the oxidation state of an element indicates that it has lost electrons, which means it is oxidized.
Correct Answer:
A
— It is oxidized
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Q. In a redox reaction, the substance that gains electrons is called: (2021)
A.
Oxidizing agent
B.
Reducing agent
C.
Reducing agent
D.
None of the above
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Solution
The substance that gains electrons in a redox reaction is called the oxidizing agent.
Correct Answer:
A
— Oxidizing agent
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Q. In a redox reaction, what happens to the oxidation state of the reducing agent? (2021)
A.
Increases
B.
Decreases
C.
Remains the same
D.
Varies
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Solution
The oxidation state of the reducing agent decreases as it loses electrons during the reaction.
Correct Answer:
B
— Decreases
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Q. In a redox reaction, which of the following statements is true? (2020)
A.
Oxidation involves gain of electrons
B.
Reduction involves loss of electrons
C.
Oxidation state of an element decreases during oxidation
D.
Reduction involves gain of electrons
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Solution
Reduction is defined as the gain of electrons, which decreases the oxidation state of the element.
Correct Answer:
D
— Reduction involves gain of electrons
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Q. In the electrochemical cell, what occurs at the anode? (2022)
A.
Reduction
B.
Oxidation
C.
Neutralization
D.
Precipitation
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Solution
At the anode of an electrochemical cell, oxidation occurs, which involves the loss of electrons.
Correct Answer:
B
— Oxidation
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Q. In the electrochemical cell, which electrode is the site of reduction? (2023)
A.
Anode
B.
Cathode
C.
Salt bridge
D.
Electrolyte
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Solution
In an electrochemical cell, the cathode is the electrode where reduction occurs.
Correct Answer:
B
— Cathode
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Q. In the electrochemical series, which element is the best reducing agent? (2022)
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Solution
Li is the best reducing agent among the given alkali metals due to its low ionization energy.
Correct Answer:
A
— Li
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Q. In the electrochemical series, which element is the strongest oxidizing agent? (2023)
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Solution
Fluorine (F2) is the strongest oxidizing agent in the electrochemical series due to its high electronegativity and tendency to gain electrons.
Correct Answer:
B
— F2
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Q. In the electrochemical series, which of the following has the highest reduction potential? (2022)
A.
Li+
B.
Na+
C.
K+
D.
F+
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Solution
Fluorine (F+) has the highest reduction potential in the electrochemical series, indicating it is a strong oxidizing agent.
Correct Answer:
D
— F+
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Q. In the reaction 2Ag+ + Zn → 2Ag + Zn^2+, which element is oxidized? (2020)
A.
Ag
B.
Zn
C.
O
D.
None of the above
Show solution
Solution
In this reaction, zinc (Zn) is oxidized as it loses electrons to form Zn^2+.
Correct Answer:
B
— Zn
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Q. In the reaction 2Ag⁺ + Zn → 2Ag + Zn²⁺, which species is reduced? (2023)
A.
Ag⁺
B.
Zn
C.
Ag
D.
Zn²⁺
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Solution
In this reaction, Ag⁺ gains electrons to form Ag, thus it is reduced.
Correct Answer:
A
— Ag⁺
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Q. In the reaction 2Fe2O3 + 3C → 4Fe + 3CO2, which species is oxidized? (2019)
A.
Fe2O3
B.
C
C.
Fe
D.
CO2
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Solution
In this reaction, carbon (C) is oxidized as it loses electrons to form CO2.
Correct Answer:
B
— C
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Q. In the reaction 2Fe²⁺ + 2e⁻ → 2Fe, what is being reduced? (2021)
A.
Fe²⁺
B.
Fe
C.
e⁻
D.
None of the above
Show solution
Solution
In this reaction, Fe²⁺ is being reduced as it gains electrons to form Fe.
Correct Answer:
A
— Fe²⁺
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Q. In the reaction 2Fe²⁺ + 2MnO4⁻ → 2Fe³⁺ + 2Mn²⁺, what is the oxidation state change for iron? (2021)
A.
+2 to +3
B.
+3 to +2
C.
0 to +2
D.
−2 to 0
Show solution
Solution
Iron changes its oxidation state from +2 to +3, indicating that it is oxidized.
Correct Answer:
A
— +2 to +3
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Q. In the reaction 2Fe²⁺ + Cl2 → 2Fe³⁺ + 2Cl⁻, what is being oxidized? (2021)
A.
Fe²⁺
B.
Cl2
C.
Fe³⁺
D.
Cl⁻
Show solution
Solution
In this reaction, Fe²⁺ is being oxidized to Fe³⁺ as it loses electrons.
Correct Answer:
A
— Fe²⁺
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Q. In the reaction 2Fe²⁺ + Cl2 → 2Fe³⁺ + 2Cl⁻, which element is oxidized? (2021)
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Solution
Iron (Fe) is oxidized from +2 to +3 oxidation state in this reaction.
Correct Answer:
A
— Fe
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Q. In the reaction 2MnO4- + 5C2O4^2- + 16H+ → 2Mn^2+ + 10CO2 + 8H2O, what is being oxidized? (2019)
A.
MnO4-
B.
C2O4^2-
C.
H+
D.
CO2
Show solution
Solution
C2O4^2- (oxalate ion) is being oxidized to CO2 in this reaction.
Correct Answer:
B
— C2O4^2-
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Q. In the reaction 2MnO4^- + 5C2O4^2- + 6H+ → 2Mn^2+ + 10CO2 + 3H2O, what is the role of MnO4^-? (2023)
A.
Oxidizing agent
B.
Reducing agent
C.
Neutral agent
D.
Catalyst
Show solution
Solution
MnO4^- acts as an oxidizing agent as it gains electrons and is reduced to Mn^2+.
Correct Answer:
A
— Oxidizing agent
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Q. In the reaction 2MnO4⁻ + 5C2O4²⁻ + 16H⁺ → 2Mn²⁺ + 10CO2 + 8H2O, which species is reduced? (2019)
A.
MnO4⁻
B.
C2O4²⁻
C.
H⁺
D.
CO2
Show solution
Solution
In this reaction, MnO4⁻ is reduced to Mn²⁺ as it gains electrons.
Correct Answer:
A
— MnO4⁻
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Q. In the reaction Zn + Cu²⁺ → Zn²⁺ + Cu, which element is oxidized? (2022)
A.
Zn
B.
Cu²⁺
C.
Zn²⁺
D.
Cu
Show solution
Solution
Zinc (Zn) is oxidized as it loses electrons to form Zn²⁺.
Correct Answer:
A
— Zn
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Q. What is the balanced equation for the redox reaction between Cr2O7^2- and Fe^2+ in acidic medium? (2020)
A.
Cr2O7^2- + 6Fe^2+ → 2Cr^3+ + 3Fe^3+
B.
Cr2O7^2- + 3Fe^2+ → 2Cr^3+ + 3Fe^3+
C.
Cr2O7^2- + 4Fe^2+ → 2Cr^3+ + 4Fe^3+
D.
Cr2O7^2- + 2Fe^2+ → 2Cr^3+ + Fe^3+
Show solution
Solution
The balanced equation in acidic medium is Cr2O7^2- + 6Fe^2+ → 2Cr^3+ + 3Fe^3+.
Correct Answer:
A
— Cr2O7^2- + 6Fe^2+ → 2Cr^3+ + 3Fe^3+
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Q. What is the change in oxidation state of carbon in the reaction C6H12O6 → 2C2H5OH? (2023)
Show solution
Solution
In the conversion of glucose to ethanol, the oxidation state of carbon decreases, indicating a reduction of -1.
Correct Answer:
C
— -1
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Q. What is the change in oxidation state of manganese in the reaction MnO4- + 8H+ + 5e- → Mn2+ + 4H2O? (2023)
A.
+7 to +2
B.
+2 to +7
C.
0 to +2
D.
+4 to +2
Show solution
Solution
Manganese changes from +7 in MnO4- to +2 in Mn2+, indicating a reduction.
Correct Answer:
A
— +7 to +2
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Q. What is the oxidation state of nitrogen in NH4Cl? (2023)
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Solution
In NH4Cl, the oxidation state of nitrogen is -3, as it is bonded to four hydrogens.
Correct Answer:
A
— -3
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Q. What is the primary characteristic of a redox reaction? (2023)
A.
Transfer of protons
B.
Transfer of electrons
C.
Change in temperature
D.
Change in pressure
Show solution
Solution
The primary characteristic of a redox reaction is the transfer of electrons between species.
Correct Answer:
B
— Transfer of electrons
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Showing 1 to 30 of 45 (2 Pages)
Physical Chemistry - Redox Reactions MCQ & Objective Questions
Understanding "Physical Chemistry - Redox Reactions" is crucial for students preparing for school and competitive exams in India. This topic not only forms a significant part of the syllabus but also helps in developing a strong conceptual foundation. Practicing MCQs and objective questions on redox reactions enhances your exam readiness and boosts your confidence, allowing you to tackle important questions effectively.
What You Will Practise Here
Definition and significance of redox reactions
Oxidation and reduction processes with examples
Balancing redox reactions using half-reaction method
Standard electrode potentials and their applications
Electrochemical cells and their functioning
Applications of redox reactions in real-life scenarios
Common redox reaction equations and their derivations
Exam Relevance
The topic of redox reactions is frequently featured in CBSE, State Boards, NEET, and JEE exams. Students can expect questions that require them to identify oxidizing and reducing agents, balance chemical equations, and apply concepts to solve numerical problems. Common question patterns include direct MCQs, assertion-reason type questions, and application-based scenarios that test conceptual understanding.
Common Mistakes Students Make
Confusing oxidation with reduction due to similar terminologies
Neglecting to balance charges and atoms in redox equations
Overlooking the significance of standard electrode potentials
Misinterpreting the role of catalysts in redox reactions
FAQs
Question: What are redox reactions?Answer: Redox reactions are chemical processes that involve the transfer of electrons between two substances, resulting in changes in their oxidation states.
Question: How can I effectively balance redox reactions?Answer: You can balance redox reactions using the half-reaction method, which involves separating the oxidation and reduction processes and balancing them individually.
Now is the time to enhance your understanding of "Physical Chemistry - Redox Reactions". Solve practice MCQs and test your knowledge to ensure you are well-prepared for your exams. Remember, consistent practice leads to success!
