Redox Reactions MCQs Quiz | Class 10
This quiz is specifically designed for Class X Science (Code 086) students, focusing on Unit I: Chemical Substances – Nature and Behaviour. It covers the core concepts of Redox Reactions, including the simultaneous occurrence of oxidation and reduction, identifying oxidizing and reducing agents, and analyzing real-world examples. Test your knowledge with these 10 MCQs, submit your answers to check your score, and download the complete solution PDF for your exam preparation.
Understanding Redox Reactions
Redox reactions, short for Reduction-Oxidation reactions, are chemical processes where oxidation and reduction occur simultaneously. These reactions involve the transfer of electrons or the transfer of oxygen and hydrogen between reactants.
1. Classical Concept of Oxidation and Reduction
- Oxidation: Defined as the addition of oxygen to a substance or the removal of hydrogen from a substance.
- Reduction: Defined as the addition of hydrogen to a substance or the removal of oxygen from a substance.
2. Electronic Concept
In terms of electron transfer, the definitions are more precise:
- Oxidation: Loss of electrons by an atom, molecule, or ion.
- Reduction: Gain of electrons by an atom, molecule, or ion.
Mnemonic: OIL RIG (Oxidation Is Loss, Reduction Is Gain).
3. Oxidizing and Reducing Agents
| Term | Action on Itself | Action on Other |
|---|---|---|
| Oxidizing Agent | Gets Reduced | Oxidizes the other substance |
| Reducing Agent | Gets Oxidized | Reduces the other substance |
4. Example Analysis
Consider the reaction: CuO + H₂ → Cu + H₂O
- CuO loses oxygen to form Cu (Reduction).
- H₂ gains oxygen to form H₂O (Oxidation).
- Therefore, CuO is the Oxidizing Agent and H₂ is the Reducing Agent.
5. Effects in Everyday Life
Corrosion: The slow eating away of metals by the action of air, moisture, or chemicals (e.g., Rusting of iron).
Rancidity: The oxidation of fats and oils in food resulting in unpleasant smell and taste. It is prevented by adding antioxidants or packing food in nitrogen gas.
Extra Practice Questions
- Identify the substance oxidized in: 2PbO + C → 2Pb + CO₂.
- Name the reducing agent in the reaction: MnO₂ + 4Al → 3Mn + 2Al₂O₃.
- Why is respiration considered an exothermic redox reaction?
- What is the color change when copper powder is heated in air?
- Write the chemical formula for rust.
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