CN  ChemNexa

Redox Reactions and Electrochemistry JEE Main MCQ & Practice Questions

Practice Redox Reactions and Electrochemistry MCQs for JEE Main Chemistry with answers, explanations, chapter revision and related ChemNexa mock tests.

Register Free for Full Chemistry Practice

Redox Reactions and Electrochemistry Revision Guide for JEE Main Chemistry

Redox Reactions focuses on electron transfer and oxidation-state changes. It supports electrochemistry, inorganic reactions and many analytical calculations.

For JEE Main Chemistry, practise oxidation-number rules, identifying oxidising and reducing agents, balancing redox equations and equivalent concepts where they are part of the syllabus.

Important Topics

  • Oxidation number rules
  • Oxidation and reduction
  • Oxidising and reducing agents
  • Balancing by oxidation-number method
  • Ion-electron method
  • Redox stoichiometry

Important Formulae & Relationships

  • Increase in oxidation number = oxidation
  • Decrease in oxidation number = reduction
  • Total electrons lost = total electrons gained in a balanced redox process

Use formulas only after checking the required units, sign convention and assumptions for the question.

What to practise in Redox Reactions and Electrochemistry

Concept Revision

Revise definitions, principles, equations, trends and core ideas from Redox Reactions and Electrochemistry before attempting MCQs.

Exam-style MCQs

Use chapter-focused multiple-choice practice to improve accuracy, recall and application for JEE Main Chemistry.

Performance Practice

Attempt ChemNexa tests, review results and return to weak areas for another round of targeted revision.

Top 20 Redox Reactions and Electrochemistry MCQs with Answers

These public questions are selected from the exact Redox Reactions and Electrochemistry chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

1. Reduction is defined as:

  • A. Increase in oxidation number
  • B. Gain of electrons
  • C. Loss of electrons
  • D. Gain of oxygen
Answer: B
Explanation: Reduction involves electron gain and a decrease in oxidation number.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

2. JEE Main advanced: Reduction is defined as:

  • A. Loss of electrons
  • B. Gain of oxygen
  • C. Increase in oxidation number
  • D. Gain of electrons
Answer: D
Explanation: Reduction involves electron gain and a decrease in oxidation number.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

3. Redox-electrochemistry reasoning: Reduction is defined as:

  • A. Increase in oxidation number
  • B. Gain of electrons
  • C. Loss of electrons
  • D. Gain of oxygen
Answer: B
Explanation: Reduction involves electron gain and a decrease in oxidation number.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

4. Oxidation is defined as:

  • A. Gain of hydrogen only
  • B. Decrease in oxidation number
  • C. Loss of electrons
  • D. Gain of electrons
Answer: C
Explanation: Oxidation involves electron loss and an increase in oxidation number.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

5. Oxidation number of an element in its free state is:

  • A. -1
  • B. Equal to atomic number
  • C. 0
  • D. +1
Answer: C
Explanation: An uncombined element has oxidation number zero.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

6. Oxidation number of oxygen in H2O2 is:

  • A. +1
  • B. -1
  • C. -2
  • D. 0
Answer: B
Explanation: Peroxide oxygen has oxidation number -1.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

7. Oxidation number of hydrogen in NaH is:

  • A. -1
  • B. +1
  • C. 0
  • D. +2
Answer: A
Explanation: Hydrogen is -1 in metal hydrides.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

8. Oxidation number of sulfur in H2SO4 is:

  • A. +4
  • B. +2
  • C. -2
  • D. +6
Answer: D
Explanation: 2(+1)+S+4(-2)=0 gives S=+6.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

9. Oxidation number of Mn in KMnO4 is:

  • A. +4
  • B. +2
  • C. +7
  • D. +6
Answer: C
Explanation: K is +1 and O is -2, giving Mn=+7.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

10. Oxidation number of Cr in K2Cr2O7 is:

  • A. +7
  • B. +6
  • C. +3
  • D. +2
Answer: B
Explanation: 2(+1)+2Cr+7(-2)=0 gives Cr=+6.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

11. A reaction in which oxidation and reduction occur simultaneously is called:

  • A. Redox reaction
  • B. Neutralisation reaction
  • C. Precipitation reaction
  • D. Hydrolysis
Answer: A
Explanation: Electron loss and gain occur together in redox reactions.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

12. Disproportionation is a reaction in which one species is:

  • A. Neither
  • B. Both oxidised and reduced
  • C. Only oxidised
  • D. Only reduced
Answer: B
Explanation: The same element undergoes both oxidation and reduction.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

13. Corrosion of iron is an example of:

  • A. Neutralisation
  • B. Photochemical decomposition
  • C. Electrochemical oxidation
  • D. Reduction only
Answer: C
Explanation: Rusting involves anodic oxidation coupled with cathodic reduction.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

14. JEE Main advanced: Oxidation is defined as:

  • A. Loss of electrons
  • B. Gain of electrons
  • C. Gain of hydrogen only
  • D. Decrease in oxidation number
Answer: A
Explanation: Oxidation involves electron loss and an increase in oxidation number.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

15. JEE Main advanced: Oxidation number of an element in its free state is:

  • A. 0
  • B. +1
  • C. -1
  • D. Equal to atomic number
Answer: A
Explanation: An uncombined element has oxidation number zero.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

16. JEE Main advanced: Oxidation number of oxygen in H2O2 is:

  • A. -2
  • B. 0
  • C. +1
  • D. -1
Answer: D
Explanation: Peroxide oxygen has oxidation number -1.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

17. JEE Main advanced: Oxidation number of hydrogen in NaH is:

  • A. 0
  • B. +2
  • C. -1
  • D. +1
Answer: C
Explanation: Hydrogen is -1 in metal hydrides.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

18. JEE Main advanced: Oxidation number of sulfur in H2SO4 is:

  • A. -2
  • B. +6
  • C. +4
  • D. +2
Answer: B
Explanation: 2(+1)+S+4(-2)=0 gives S=+6.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

19. JEE Main advanced: Oxidation number of Mn in KMnO4 is:

  • A. +7
  • B. +6
  • C. +4
  • D. +2
Answer: A
Explanation: K is +1 and O is -2, giving Mn=+7.

JEE Main Chemistry · Redox Reactions and Electrochemistry · Very Very Hard

20. JEE Main advanced: Oxidation number of Cr in K2Cr2O7 is:

  • A. +3
  • B. +2
  • C. +7
  • D. +6
Answer: D
Explanation: 2(+1)+2Cr+7(-2)=0 gives Cr=+6.

Login to Start Full Test

Redox Reactions and Electrochemistry Practice Tests

Redox Reactions and Electrochemistry Frequently Asked Questions

How do I identify the oxidising agent?

The oxidising agent causes another species to be oxidised and is itself reduced.

What is the safest way to balance redox equations?

Use either the oxidation-number method or ion-electron method systematically, then verify both atom balance and total charge.

Why is oxidation state useful?

It provides a bookkeeping method for identifying electron-transfer changes even when electrons do not appear explicitly in the written equation.

Continue with another chapter to build connected concepts and strengthen your overall Chemistry preparation.

Continue JEE Main Chemistry

View all JEE Main chapters and testsBrowse all Chemistry PracticeCreate a free account