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CBSE Class 11 Chemistry MCQs: Balancing Redox Equations by Ion-Electron Method
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Free Online Test: CBSE Class 11 Chemistry Redox Equations and Ion-Electron Balancing
Introduction Paragraph
Balancing redox equations is one of the most essential skills in Inorganic Chemistry for CBSE Class 11 students. The Ion-Electron Method provides a systematic approach to balance oxidation and reduction half-reactions while conserving both mass and charge. This concept is crucial for understanding oxidation numbers, electron transfer, and redox titrations, forming the foundation for advanced topics in physical and electrochemistry.
This online MCQ practice test focuses on Balancing Redox Equations by the Ion-Electron Method and is designed strictly as per the NCERT Class 11 Chemistry syllabus and CBSE Board exam standards. Each question is carefully framed to test conceptual clarity, logical reasoning, and the ability to apply the method correctly in acidic and basic mediums.
With automatic scoring and detailed explanations, this test offers an interactive way to strengthen your understanding of redox balancing — perfect for board preparation and competitive exams like JEE and NEET.
Sample MCQs (with Answers and Explanations)
Q1. In acidic medium, the correct balanced half-reaction for reduction of permanganate ion to Mn²⁺ is:
A) MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O
B) MnO₄⁻ + 4H⁺ + 2e⁻ → MnO₂ + 2H₂O
C) MnO₄⁻ + e⁻ → MnO₄²⁻
D) MnO₄⁻ → MnO₂
Answer: A) MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O
Explanation: In acidic solution, Mn⁷⁺ is reduced to Mn²⁺ by gaining five electrons, producing water molecules.
Q2. In basic medium, which step is added after balancing H⁺ and H₂O in the ion-electron method?
A) Add OH⁻ ions to neutralize H⁺ ions
B) Add more H₂O
C) Multiply the reaction by 2
D) Ignore charge balance
Answer: A) Add OH⁻ ions to neutralize H⁺ ions
Explanation: In basic medium, H⁺ is neutralized with OH⁻ to form water and maintain charge balance.
Q3. The oxidation number of Cl changes from -1 to +5 in the reaction Cl⁻ → ClO₃⁻. How many electrons are lost?
A) 6 B) 4 C) 2 D) 8
Answer: A) 6
Explanation: Change in oxidation number = +5 – (-1) = 6; hence, 6 electrons are lost in oxidation.
Q4. For the half-reaction Fe²⁺ → Fe³⁺ + e⁻, the species is:
A) Reduced B) Oxidized C) Both D) Unchanged
Answer: B) Oxidized
Explanation: Fe²⁺ loses one electron to form Fe³⁺; loss of electrons indicates oxidation.
Q5. In the reaction H₂O₂ → O₂ (acidic medium), number of electrons transferred per molecule of H₂O₂ is:
A) 2 B) 1 C) 3 D) 4
Answer: A) 2
Explanation: Hydrogen peroxide decomposes as H₂O₂ → O₂ + 2H⁺ + 2e⁻; hence, two electrons are involved.
✅ Highlight:
These MCQs follow the NCERT Class 11 Chemistry syllabus and provide conceptual understanding with detailed solutions — ideal for CBSE board exams and entrance preparation.