Oxidation and Reduction Quiz - CBSE Class 12 Chemistry

Free practice quiz: Oxidation and Reduction (CBSE Class 12 Chemistry). 12 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This CBSE Class 12 Chemistry practice quiz has 12 multiple-choice questions on Oxidation and Reduction, and 12 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. Which of the following represents oxidation?

   1. Gain of electrons
   2. Loss of electrons
   3. Gain of hydrogen
   4. Gain of oxygen
   Show answer

   Answer: B. Loss of electrons

   Oxidation is defined as the loss of electrons by an atom, ion, or molecule.

2. In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, which species is oxidized?

   1. Zn
   2. Cu
   3. SO₄²⁻
   4. Cu²⁺
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   Answer: A. Zn

   Zn loses electrons and becomes Zn²⁺, thus undergoing oxidation.

3. Identify the oxidizing agent in the reaction 2Fe³⁺ + Sn²⁺ → 2Fe²⁺ + Sn⁴⁺

   1. Fe³⁺
   2. Sn²⁺
   3. Fe²⁺
   4. Sn⁴⁺
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   Answer: A. Fe³⁺

   Fe³⁺ accepts electrons from Sn²⁺, causing its own reduction and the oxidation of Sn²⁺. Thus, Fe³⁺ is the oxidizing agent.

4. Explain why the oxidation state of oxygen is usually -2, but it can be different in peroxides and superoxides.

   1. Due to electronegativity differences
   2. Due to the presence of lone pairs
   3. Due to the formation of covalent bonds
   4. Due to the presence of unpaired electrons
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   Answer: A. Due to electronegativity differences

   Oxygen is highly electronegative, usually attracting two electrons to achieve a stable octet. However, peroxides (O₂²⁻) and superoxides (O₂⁻) have different structures leading to different oxidation states.

5. Discuss the application of redox reactions in the extraction of metals from their ores. Explain with the example of iron extraction.

   1. Redox reactions are irrelevant
   2. Redox reactions are used in some cases
   3. Redox reactions are used in most cases
   4. Redox reactions are used in all cases
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   Answer: D. Redox reactions are used in all cases

   Extraction of metals involves reduction of metal ions in ores using a reducing agent. In the case of iron, reduction of iron(III) oxide with carbon monoxide in a blast furnace is a key step.

More questions in this quiz

Answers and explanations are in the full quiz.

1. Which of the following represents reduction?
2. In the reaction Fe²⁺ + 2e⁻ → Fe, which species is reduced?
3. Identify the reducing agent in the reaction 2Fe³⁺ + Sn²⁺ → 2Fe²⁺ + Sn⁴⁺
4. Balance the following redox reaction in acidic medium: Cr₂O₇²⁻ + Fe²⁺ → Cr³⁺ + Fe³⁺
5. Describe the process of disproportionation with a suitable example.
6. Explain the concept of electrochemical series and its significance in predicting the spontaneity of redox reactions.
7. Derive the Nernst equation and explain how it is used to calculate the cell potential under non-standard conditions.

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