13th Chapter Solved Exercise MCQs of FSC Second Year Chemistry
written by Almas AnwarThe 13th Chapter Solved Exercise MCQs of FSC 2nd-year Chemistry provides a complete set of solved multiple-choice questions (MCQs). Each MCQ comes with a brief explanation to help you understand the correct answer. These solutions are designed to support students in preparing for their exams, making complex concepts easier to grasp and ensuring a solid foundation for success.
13th chapter solved MCQs with explanation
1. Acetic acid is manufactured by:
(a) distillation
(b) fermentation
(c) ozonolysis
(d) esterification
Explanation: Option (b) is correct. Because acetic acid is commonly manufactured through the fermentation of ethanol by bacteria, especially Acetobacter. This biological process converts ethanol into acetic acid under aerobic conditions. Distillation, ozonolysis, and esterification are not involved in its industrial production.
2. A carboxylic acid contains:
(a) a hydroxyl group
(b) a carboxyl group
(c) a hydroxyl and carboxyl group
(d) a carboxyl and an aldehydic group
Explanation: Option (c) is correct. Because a carboxylic acid contains a carboxyl group (-COOH), which is made up of a hydroxyl group (-OH) and a carbonyl group (C=O). These two functional groups together form the characteristic carboxyl group of carboxylic acids.
3. Which acid is used in the manufacture of synthetic fiber:
(a) formic acid
(b) oxalic acid
(c) carbonic acid
(d) acetic acid
Explanation: Option (d) is correct. Because acetic acid is used in the production of synthetic fibers, especially acetate fibers, which are made from cellulose combined with acetic acid. These fibers are used in textiles and clothing. Other acids listed are not commonly involved in synthetic fiber manufacturing.
4. Which following derivative can’t be prepared directly from acetic acid:
(a) acetamide
(b) acetyl chloride
(c) acetic anhydride
(d) ethyl acetate
Explanation: Option (c) is correct. Because acetic anhydride cannot be prepared directly from acetic acid. It requires a dehydrating agent (such as phosphorus pentaoxide) to remove water and form the anhydride. In contrast, acetamide, acetyl chloride, and ethyl acetate can be directly prepared from acetic acid using appropriate reagents like ammonia, thionyl chloride, and ethanol, respectively.
5. Which reagent is used to reduce a carboxylic group to an alcohol?
(a) H₂/Ni
(b) H₂/Pt
(c) NaBH₄
(d) LiAlH₄
Explanation: Option (d) is correct. Because lithium aluminum hydride (LiAlH₄) is a strong reducing agent that is commonly used to reduce carboxylic acids to primary alcohols. Other options, like NaBH₄, are weaker and typically reduce aldehydes and ketones but not carboxylic acids.
6. The solution of which acid is used for seasoning of food:
(a) formic acid
(b) acetic acid
(c) benzoic acid
(d) butanoic acid
Explanation: Option (b) is correct. Because acetic acid is commonly found in vinegar, which is widely used for seasoning food. It has a sour taste and acts as a preservative as well. The other acids listed are not typically used for food seasoning.
7. Organic compounds X and Y react together to form organic compound Z. What type of compounds can X, Y, and Z be?
(a) alcohol ester acid
(b) acid ester alcohol
(c) ester alcohol acid
(d) alcohol acid ester
Explanation: Option (d) is correct. Because when an alcohol reacts with an acid, an ester is formed in a reaction known as esterification. In this reaction:
- X is alcohol
- Y is acid
- Z is ester
This process typically involves the removal of water (dehydration), with the -OH group from the acid and a hydrogen atom from the alcohol forming water.
8. An aqueous solution of an organic compound reacts with sodium carbonate to produce carbon dioxide gas. Which one of the following could be the organic compound?
(a) CH₂ = CH – CH₃
(b) CH₃ – CHO
(c) CH₃COO – C₂H₅
(d) CH₃ – CH₂ – COOH
Explanation: Option (d) is correct. Because carboxylic acids, like propanoic acid, react with sodium carbonate (Na₂CO₃) to produce carbon dioxide (CO₂) gas.
The reaction is:
2CH₃CH₂COOH + Na₂CO₃ → 2CH₃CH₂COONa + CO₂ + H₂O
This occurs because carboxylic acids are acidic enough to react with carbonate salts, releasing CO₂. Other compounds (a, b, and c) do not have acidic hydrogens capable of reacting with sodium carbonate to produce carbon dioxide gas.
9. Which of the following is not a fatty acid?
(a) propanoic acid
(b) acetic acid
(c) phthalic acid
(d) butanoic acid
Explanation: Option (c) is correct. Because fatty acids are carboxylic acids with long hydrocarbon chains (usually with 4 to 28 carbon atoms).
- Propanoic acid, acetic acid, and butanoic acid are simple carboxylic acids that can be considered short-chain fatty acids.
- Phthalic acid, however, is an aromatic dicarboxylic acid and does not fit the definition of a fatty acid because it has a benzene ring instead of a long hydrocarbon chain.
10. Acetamide is prepared by:
(a) heating ammonium acetate
(b) heating methyl cyanide
(c) heating ethyl acetate
(d) the hydrolysis of methyl cyanide
Explanation: Option (a) is correct. Because acetamide (CH₃CONH₂) is prepared by heating ammonium acetate (CH₃COONH₄). This process, known as the “dehydration of ammonium acetate,” results in the formation of acetamide and water.
CH₃COONH₄ → CH₃CONH₂ + H₂O
The other options are incorrect because:
- (b) Heating methyl cyanide (acetonitrile) does not produce acetamide.
- (c) Heating ethyl acetate does not produce acetamide directly.
- (d) Hydrolysis of methyl cyanide produces acetic acid and ammonia, not acetamide.
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