Alcohols, Phenols and Ethers Quiz - ICSE Class 12 Chemistry
Free practice quiz: Alcohols, Phenols and Ethers (ICSE Class 12 Chemistry). 10 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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Which of the following is an incorrect statement regarding ethers?
- Ethers are generally less polar than alcohols.
- Ethers are good solvents for many organic compounds.
- Ethers can be prepared by the acid-catalyzed hydration of alkenes.
- Ethers are relatively unreactive towards most common reagents.
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Answer: C. Ethers can be prepared by the acid-catalyzed hydration of alkenes.
Acid-catalyzed hydration of alkenes produces alcohols, not ethers. Ethers are typically prepared by Williamson ether synthesis or by the dehydration of alcohols.
Which of the following alcohols is chiral?
- Ethanol
- Propan-1-ol
- Propan-2-ol
- Butan-2-ol
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Answer: D. Butan-2-ol
Chirality arises from a carbon atom bonded to four different groups. In butan-2-ol, the carbon atom at position 2 is bonded to a methyl group, a hydrogen atom, a hydroxyl group, and an ethyl group, making it a chiral center.
Which functional group is present in phenol?
- Alcoholic hydroxyl
- Phenolic hydroxyl
- Ether
- Carboxylic acid
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Answer: B. Phenolic hydroxyl
Phenol has a hydroxyl (-OH) group directly attached to an aromatic benzene ring. This is specifically termed a phenolic hydroxyl group, which differs in properties from an alcoholic hydroxyl group attached to an aliphatic carbon.
Which of the following is NOT a characteristic reaction of phenol?
- Electrophilic substitution on the ring
- Reaction with sodium metal
- Acidity and salt formation
- Oxidation to a ketone
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Answer: D. Oxidation to a ketone
Phenol undergoes electrophilic substitution readily due to the activating effect of the -OH group. It reacts with sodium metal to form sodium phenoxide. It is acidic and forms salts with bases. However, phenol cannot be oxidized to a ketone because it lacks the necessary structure. Oxidation of phenol under strong conditions typically leads to ring cleavage or quinone formation, not a simple ketone.
The dehydration of propan-1-ol using concentrated H2SO4 at 170°C yields:
- Propene
- Propanal
- Propan-2-ol
- Dipropyl ether
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Answer: A. Propene
When primary alcohols like propan-1-ol are heated with concentrated sulfuric acid at 170°C, they undergo intramolecular dehydration (elimination) to form alkenes. In this case, propene is formed.