Chemical Properties of Carbon Compounds: Oxidation MCQs Quiz | Class 10
This Class X Science (Code 086) quiz covers Unit I: Chemical Substances – Nature and Behaviour, focusing specifically on the Chemical Properties of Carbon Compounds and Oxidation reactions. The quiz tests your knowledge of how carbon compounds, such as ethanol, are oxidized to form carboxylic acids using common oxidizing agents like alkaline KMnO4 or acidified K2Cr2O7. Complete the 10 MCQs below and click ‘Submit Quiz’ to view your score and detailed explanations. You can then download a PDF answer sheet for your exam preparation.
Understanding Oxidation in Carbon Compounds
In the study of carbon compounds, oxidation is a chemical property where a substance gains oxygen or loses hydrogen. While combustion is a form of oxidation that completely breaks down the molecule into carbon dioxide and water with the release of heat and light, controlled oxidation allows for the conversion of carbon compounds into specific functional groups without breaking the carbon chain completely.
1. Oxidation of Alcohols
One of the most important reactions in Class 10 Chemistry is the oxidation of alcohols to carboxylic acids. Ethanol (an alcohol) can be converted into ethanoic acid (a carboxylic acid) by heating it with specific chemical substances known as oxidizing agents.
The General Reaction:
Ethanol + [Oxygen from Oxidizing Agent] -> Ethanoic Acid + Water
Chemical Equation:
CH3CH2OH + 2[O] -> CH3COOH + H2O
2. Oxidizing Agents
Oxidizing agents are substances that have the ability to give oxygen to other substances or remove hydrogen from them. In the context of carbon compounds, two primary agents are used:
- Alkaline Potassium Permanganate (KMnO4): A strong oxidizing agent that is purple in color. When it oxidizes ethanol, the purple color fades or disappears as it is reduced.
- Acidified Potassium Dichromate (K2Cr2O7): Another strong oxidizing agent, typically orange in color. It turns green upon reduction during the reaction.
Summary Table of Agents
| Agent Name | Formula | Condition | Role |
|---|---|---|---|
| Potassium Permanganate | KMnO4 | Alkaline (Basic) + Heat | Provides oxygen to alcohol |
| Potassium Dichromate | K2Cr2O7 | Acidified + Heat | Provides oxygen to alcohol |
Quick Revision Points
- Carbon compounds can be oxidized on combustion.
- Alcohols turn into carboxylic acids upon oxidation.
- This reaction is distinct from combustion because it stops at the acid stage and does not produce only CO2 and H2O.
- Heat is usually required for these reactions to proceed at a measurable rate.
Extra Practice Questions
- Write the formula for Ethanoic acid. (Answer: CH3COOH)
- What happens to the purple color of KMnO4 when added dropwise to warm ethanol? (Answer: It fades/disappears initially)
- Is the conversion of ethanol to ethanoic acid a reduction or oxidation reaction? (Answer: Oxidation)
- Name the functional group present in the product of ethanol oxidation. (Answer: Carboxylic Acid group / -COOH)
- Why is alkaline KMnO4 added drop by drop? (Answer: To ensure complete reaction and observe the endpoint color change)
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