Try each question on your own first. Use the Show Answer button only after you have selected your option, then read the explanation and revise the related concept from your chapter notes.
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.
