Class 12 Chemistry MCQ – Alcohols, Phenols, and Ethers

1. Which of the following is a secondary alcohol?

a) Methanol
b) Ethanol
c) Propan-2-ol
d) Phenol

Answer:

c) Propan-2-ol

Explanation:

In secondary alcohols, the OH group is attached to a carbon atom that is bonded to two other carbon atoms.

2. Which compound is formed on oxidation of propan-2-ol?

a) Propanal
b) Propanoic acid
c) Propane
d) Propene

Answer:

a) Propanal

Explanation:

Secondary alcohols on oxidation give ketones.

3. Which of the following ethers can be prepared using Williamson ether synthesis?

a) Diethyl ether
b) Dimethyl ether
c) Ethyl methyl ether
d) Phenyl ethyl ether

Answer:

a) Diethyl ether

Explanation:

Williamson ether synthesis involves the reaction of an alkoxide ion with a primary alkyl halide.

4. Phenol is less acidic than:

a) Water
b) Ethanol
c) Carboxylic acids
d) Alkynes

Answer:

b) Ethanol

Explanation:

The presence of the benzene ring in phenol stabilizes the phenoxide ion, making phenol more acidic than alcohols like ethanol.

5. The IUPAC name for the compound CH3-O-CH2-CH3 is:

a) Methoxyethane
b) Ethyl methyl ether
c) Dimethyl ether
d) Ethyl methanol

Answer:

a) Methoxyethane

Explanation:

According to IUPAC nomenclature, ethers are named as alkoxyalkanes.

6. Which of the following reagents can be used to convert phenol to 2,4,6-tribromophenol?

a) Br2 in CS2
b) Br2 in water
c) Br2 in NaOH
d) HBr

Answer:

b) Br2 in water

Explanation:

In water, bromine reacts with phenol to give 2,4,6-tribromophenol.

7. Which compound on dehydration gives ether as the major product?

a) Primary alcohol
b) Secondary alcohol
c) Tertiary alcohol
d) Phenol

Answer:

a) Primary alcohol

Explanation:

Dehydration of primary alcohols at lower temperatures predominantly yields ethers.

8. Ethers are generally resistant to:

a) Oxidation
b) Reduction
c) Halogenation
d) Hydrolysis

Answer:

a) Oxidation

Explanation:

Ethers have no hydrogen attached to the oxygen, making them resistant to oxidation.

9. Anisole is derived from:

a) Methanol
b) Ethanol
c) Phenol
d) Glycerol

Answer:

c) Phenol

Explanation:

Anisole has a methoxy group attached to a benzene ring, derived from phenol.

10. Which reagent can distinguish between tertiary alcohol and secondary alcohol?

a) Lucas reagent
b) Tollens' reagent
c) Fehling's solution
d) Sodium metal

Answer:

a) Lucas reagent

Explanation:

Tertiary alcohols react instantly with Lucas reagent while secondary alcohols take some time.

11. Ethylene glycol is used as:

a) A disinfectant
b) An antifreeze
c) A drying agent
d) A dehydrating agent

Answer:

b) An antifreeze

Explanation:

Ethylene glycol lowers the freezing point of water, making it useful as an antifreeze in cooling systems.

12. The reaction of sodium with ethanol produces:

a) Sodium ethoxide
b) Sodium ethanoate
c) Ethene
d) Ethane

Answer:

a) Sodium ethoxide

Explanation:

Sodium reacts with ethanol to give sodium ethoxide and hydrogen gas.

13. Which of the following compounds can exhibit hydrogen bonding with water?

a) Diethyl ether
b) Phenol
c) Dimethyl ether
d) Diphenyl ether

Answer:

b) Phenol

Explanation:

Phenol has an OH group capable of forming hydrogen bonds with water.

14. Which of the following alcohols is used as a disinfectant?

a) Methanol
b) Ethanol
c) Glycerol
d) Ethylene glycol

Answer:

b) Ethanol

Explanation:

Ethanol at 70% concentration is used as a disinfectant.

15. Which of the following is not a method for the preparation of ethers?

a) Williamson synthesis
b) Dehydration of alcohols
c) Grignard synthesis
d) Kolbe's reaction

Answer:

d) Kolbe's reaction

Explanation:

Kolbe's reaction is used for the synthesis of alkanes, not ethers.

16. The boiling point of alcohols is higher than ethers because of:

a) Van der Waals forces
b) Ionic bonds
c) Hydrogen bonding
d) Covalent bonding

Answer:

c) Hydrogen bonding

Explanation:

Alcohols can form intermolecular hydrogen bonds, leading to higher boiling points compared to ethers.

17. Which of the following ethers will react with HI to give 2-iodopropane as a product?

a) Dimethyl ether
b) Ethyl methyl ether
c) Diethyl ether
d) Propyl methyl ether

Answer:

d) Propyl methyl ether

Explanation:

Reaction with HI cleaves the ether linkage, giving iodide on the larger alkyl group.

18. Which of the following is a phenolic antiseptic?

a) Ethanol
b) Glycerol
c) Phenyl mercuric acetate
d) Anisole

Answer:

c) Phenyl mercuric acetate

Explanation:

Phenyl mercuric acetate is a phenolic compound used as an antiseptic.

19. The reaction of phenol with zinc dust gives:

a) Benzene
b) Anisole
c) Cyclohexanol
d) Phenylhydrazine

Answer:

a) Benzene

Explanation:

Phenol on treatment with zinc dust undergoes reduction to form benzene.

20. Which of the following ethers can form hydrogen bonds among its molecules?

a) Dimethyl ether
b) Diethyl ether
c) Ethyl methyl ether
d) None of the above

Answer:

d) None of the above

Explanation:

Ethers cannot form hydrogen bonds among their own molecules due to the absence of a hydrogen attached to the oxygen atom.

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