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1. Alcohols generally have higher boiling points than alkanes of comparable molecular mass mainly due to:
A. Intermolecular hydrogen bonding
B. Their higher molecular mass
C. Ionic character of the O-H bond
D. Van der Waals forces alone
Answer: A. Intermolecular hydrogen bonding
Explanation: The -OH group in alcohols allows hydrogen bonding between molecules, requiring more energy to separate them and raising the boiling point.
2. Phenol is more acidic than an aliphatic alcohol mainly because:
A. The phenoxide ion formed is stabilized by resonance with the benzene ring
B. Phenol has a higher molecular weight
C. Alcohols are basic in nature
D. Phenol lacks an -OH group
Answer: A. The phenoxide ion formed is stabilized by resonance with the benzene ring
Explanation: Delocalization of the negative charge on oxygen into the aromatic ring stabilizes the phenoxide ion, increasing phenol's acidity.
3. The Lucas test is used to distinguish between:
A. Primary, secondary and tertiary alcohols
B. Phenols and alcohols
C. Ethers and alcohols
D. Aldehydes and ketones
Answer: A. Primary, secondary and tertiary alcohols
Explanation: Lucas reagent (conc. HCl + anhydrous ZnCl2) reacts with alcohols at different rates depending on class, producing turbidity at different speeds.
4. The Williamson synthesis is a standard method for preparing:
A. Ethers
B. Alcohols
C. Esters
D. Aldehydes
Answer: A. Ethers
Explanation: In Williamson ether synthesis, an alkyl halide reacts with a sodium alkoxide/phenoxide via SN2 to give an ether.
5. Reaction of phenol with chloroform and NaOH (Reimer-Tiemann reaction) followed by hydrolysis gives:
A. Salicylaldehyde
B. Salicylic acid directly
C. Picric acid
D. Benzoic acid
Answer: A. Salicylaldehyde
Explanation: The Reimer-Tiemann reaction introduces a -CHO group ortho to the -OH group of phenol, forming salicylaldehyde.
6. Ethers are relatively less reactive compared to alcohols mainly because they:
A. Lack a reactive hydrogen atom attached to oxygen
B. Contain reactive double bonds
C. Are highly polar
D. Have an ionic C-O bond
Answer: A. Lack a reactive hydrogen atom attached to oxygen
Explanation: Since the oxygen in ethers is bonded to two carbon groups rather than hydrogen, ethers cannot undergo reactions typical of the O-H bond.
Explanation: Sodium phenoxide reacts with CO2 under pressure, followed by acidification, to give salicylic acid via Kolbe's reaction.
8. Acid-catalyzed dehydration of alcohols to alkenes generally follows:
A. Zaitsev's rule via an E1 mechanism
B. Markovnikov's rule for addition
C. Anti-Markovnikov's rule
D. An SN2 mechanism
Answer: A. Zaitsev's rule via an E1 mechanism
Explanation: Dehydration typically proceeds through a carbocation intermediate (E1), favoring the more substituted (more stable) alkene as per Zaitsev's rule.
9. Which of the following is the most acidic compound?
A. p-Nitrophenol
B. Phenol
C. p-Cresol
D. Ethanol
Answer: A. p-Nitrophenol
Explanation: The electron-withdrawing nitro group at the para position further stabilizes the phenoxide ion by resonance, making p-nitrophenol more acidic than phenol.
10. Heating ethanol with concentrated H2SO4 at about 413 K primarily gives:
A. Ethene
B. Diethyl ether
C. Ethanal
D. Ethanoic acid
Answer: A. Ethene
Explanation: At higher temperature (413 K), concentrated H2SO4 favors dehydration of ethanol to ethene; lower temperatures instead favor ether formation.
11. Anisole is an example of an:
A. Aromatic ether
B. Aliphatic alcohol
C. Aromatic alcohol
D. Aliphatic ether
Answer: A. Aromatic ether
Explanation: Anisole (methoxybenzene) has a methyl group attached via oxygen to a benzene ring, making it an aromatic ether.
12. Victor Meyer's test is used to identify whether an alcohol is:
A. Primary, secondary or tertiary
B. Aromatic or aliphatic
C. Saturated or unsaturated
D. Acidic or basic
Answer: A. Primary, secondary or tertiary
Explanation: The Victor Meyer test uses a series of colour changes to distinguish primary, secondary and tertiary alcohols.
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