Here below some basic MCQ’s about “Alcohols,Phenols and Ethers structure and reaction” with Answer which is explained in details for exam practice. let’s check one by one.
Question 1:
Which of the following is a primary alcohol?
A) 2-Butanol
B) 1-Butanol
C) 2-Methyl-2-propanol
D) 1-Pentanol
Answer: B) 1-Butanol
Explanation: A primary alcohol has the hydroxyl (-OH) group attached to a carbon atom that is connected to only one other carbon atom. In 1-butanol, the -OH group is attached to the terminal carbon, making it a primary alcohol.
Question 2:
Which reaction would NOT produce an ether?
A) The dehydration of two alcohol molecules
B) The reaction of an alcohol with an alkyl halide in the presence of a base
C) The condensation of a phenol with an aldehyde
D) The Williamson ether synthesis
Answer: C) The condensation of a phenol with an aldehyde
Explanation: While aldehydes can react with phenols, they typically do not form ethers directly. The condensation of a phenol with an aldehyde generally leads to products like benzyl alcohols or phenolic compounds rather than ethers.
Question 3:
Which of the following compounds is classified as a phenol?
A) Ethanol
B) Benzyl alcohol
C) Cresol
D) Cyclohexanol
Answer: C) Cresol
Explanation: Phenols are compounds that contain a hydroxyl group (-OH) directly attached to a benzene ring. Cresol is a methyl-substituted phenol, making it a phenolic compound, while the other options do not have the -OH group bonded to a benzene ring.
Question 4:
What is the primary method for the synthesis of ethers via the Williamson ether synthesis?
A) Electrophilic aromatic substitution
B) Alkylation of phenols
C) Nucleophilic substitution
D) Dehydration of alcohols
Answer: C) Nucleophilic substitution
Explanation: The Williamson ether synthesis involves the nucleophilic substitution reaction where an alkoxide ion acts as a nucleophile and attacks an alkyl halide, resulting in the formation of an ether.
Question 5:
Which statement about phenols is correct?
A) They are weaker acids than alcohols.
B) They can be dehydrated to form alkenes.
C) They are more acidic than alcohols due to resonance stabilization.
D) They cannot undergo oxidation.
Answer: C) They are more acidic than alcohols due to resonance stabilization.
Explanation: Phenols are indeed more acidic than alcohols because the negative charge that forms on the phenoxide ion (when phenol donates a proton) can be delocalized over the aromatic ring through resonance. This stabilization makes phenols more acidic compared to aliphatic alcohols.
Question 6:
Which of the following statements about alcohols is TRUE?
A) All alcohols are soluble in water.
B) Alcohols can act as both acids and bases.
C) Alcohols do not participate in hydrogen bonding.
D) Tertiary alcohols are generally more reactive in oxidation reactions than primary alcohols.
Answer: B) Alcohols can act as both acids and bases.
Explanation: Alcohols can donate a proton (acting as an acid) or accept a proton (acting as a base), making them amphoteric. While some alcohols are soluble in water, not all are, especially longer-chain alcohols. Alcohols participate in hydrogen bonding, and primary alcohols are usually more reactive in oxidation than tertiary ones.
Question 7:
What is the major product when phenol is treated with concentrated H2SO4?
A) Benzene
B) Phenyl sulfate
C) Ethyl phenyl ether
D) No reaction
Answer: B) Phenyl sulfate
Explanation: Concentrated sulfuric acid can protonate phenol, leading to the formation of phenyl sulfate as the major product through electrophilic aromatic substitution.
Question 8:
Which of the following alcohols cannot be oxidized to a carboxylic acid?
A) Ethanol
B) 1-Butanol
C) 2-Butanol
D) 1-Pentanol
Answer: C) 2-Butanol
Explanation: 2-Butanol is a secondary alcohol, which can be oxidized to a ketone but cannot be further oxidized to a carboxylic acid, while primary alcohols can be oxidized to carboxylic acids.
Question 9:
Which reagent is commonly used to convert alcohols to alkyl halides?
A) PCl3
B) K2Cr2O7
C) NaBH4
D) H2SO4
Answer: A) PCl3
Explanation: PCl3 is often used to convert alcohols to alkyl halides through a substitution reaction, forming the corresponding alkyl chloride.
Question 10:
Which of the following is a characteristic reaction of phenols?
A) Formation of Grignard reagents
B) Esterification
C) Electrophilic substitution
D) Dehydrogenation
Answer: C) Electrophilic substitution
Explanation: Phenols readily undergo electrophilic substitution reactions due to the electron-donating effect of the hydroxyl group on the aromatic ring.
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