Question 21:
Which of the following methods can be used to prepare phenol?
A) Hydrolysis of chlorobenzene
B) Reduction of benzaldehyde
C) Nitration of benzene
D) Dehydrogenation of cyclohexanol
Answer: A) Hydrolysis of chlorobenzene
Explanation: Hydrolysis of chlorobenzene in the presence of NaOH or H2O can produce phenol. The other methods do not lead to the formation of phenol.
Question 22:
What type of reaction occurs when a secondary alcohol is oxidized?
A) It forms a ketone.
B) It forms an aldehyde.
C) It remains unchanged.
D) It forms a carboxylic acid.
Answer: A) It forms a ketone.
Explanation: Secondary alcohols are oxidized to ketones, while primary alcohols can be oxidized to aldehydes and further to carboxylic acids.
Question 23:
Which of the following compounds is not soluble in water?
A) Methanol
B) Ethanol
C) Propanol
D) Octanol
Answer: D) Octanol
Explanation: Octanol, being a long-chain alcohol, has a hydrophobic tail that makes it less soluble in water compared to shorter-chain alcohols like methanol, ethanol, and propanol.
Question 24:
What happens when a phenol is subjected to electrophilic nitration?
A) It forms a nitro derivative.
B) It forms an ether.
C) It does not react.
D) It forms an aldehyde.
Answer: A) It forms a nitro derivative.
Explanation: Electrophilic nitration of phenol introduces a nitro group (-NO2) to the aromatic ring, resulting in a nitrophenol compound.
Question 25:
Which of the following compounds can undergo dehydration to form an alkene?
A) Primary alcohol
B) Secondary alcohol
C) Tertiary alcohol
D) All of the above
Answer: D) All of the above
Explanation: All types of alcohols (primary, secondary, and tertiary) can undergo dehydration reactions to form alkenes, although the conditions and products may vary.
Question 26:
What is the primary use of phenol in industry?
A) As a solvent
B) As a disinfectant
C) As a precursor for plastics
D) As a fuel
Answer: C) As a precursor for plastics
Explanation: Phenol is primarily used in the production of plastics, particularly in the synthesis of phenolic resins. It is also used in other applications but is most significant in plastics.
Question 27:
Which of the following is a characteristic of tertiary alcohols?
A) They can be oxidized to aldehydes.
B) They do not react with Jones reagent.
C) They readily undergo dehydration.
D) They are less stable than primary alcohols.
Answer: C) They readily undergo dehydration.
Explanation: Tertiary alcohols are more likely to undergo dehydration reactions to form alkenes due to the stability of the carbocation formed during the process.
Question 28:
Which reagent would you use to distinguish between a primary and a secondary alcohol?
A) KMnO4
B) NaOH
C) HBr
D) AgNO3
Answer: A) KMnO4
Explanation: Potassium permanganate (KMnO4) can oxidize primary alcohols to carboxylic acids and secondary alcohols to ketones, allowing differentiation between them.
Question 29:
Which of the following is true about the boiling points of phenols compared to alcohols?
A) Phenols have lower boiling points than alcohols.
B) Phenols have higher boiling points than alcohols due to hydrogen bonding.
C) Phenols and alcohols have similar boiling points.
D) Phenols have significantly higher boiling points than alcohols.
Answer: B) Phenols have higher boiling points than alcohols due to hydrogen bonding.
Explanation: Like alcohols, phenols can hydrogen bond, but they also have aromatic stabilization, which contributes to higher boiling points compared to non-aromatic alcohols.
Question 30:
Which of the following compounds can form an ether through the Williamson ether synthesis?
A) 1-Hexanol
B) Cyclohexanol
C) Tertiary butyl alcohol
D) Phenol
Answer: A) 1-Hexanol
Explanation: 1-Hexanol can be used in the Williamson ether synthesis as it is a primary alcohol. Tertiary alcohols and phenols are not suitable for this method due to steric hindrance.
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