Phenols( Acidic Nature, Electrophilic Substitution Reactions...) NEET Questions

Organic Chemistry - Organic Compounds Containing Oxygen

Phenols( Acidic Nature, Electrophilic Substitution Reactions...) MCQ Questions


13.
Among the following, which has the LEAST tendency to ionize in water?
A.
p-Methoxyphenol
B.
Cyclohexanol
C.
Phenol
D.
p-Cresol
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ANSWER :
B. Cyclohexanol
14.
Which of the following has the lowest pKa value?
A.
2,4-Dinitrophenol
B.
p-Chlorophenol
C.
Phenol
D.
p-Nitrophenol
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ANSWER :
A. 2,4-Dinitrophenol
15.
Phenoxide ion is more stable than alkoxide ion because:
A.
Phenoxide has more sigma bonds
B.
Phenoxide has higher hybridization
C.
Alkoxide has higher molecular mass
D.
Negative charge in phenoxide is delocalized over the ring
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ANSWER :
D. Negative charge in phenoxide is delocalized over the ring
16.
Which substituent will make phenol the LEAST acidic?
A.
-CN
B.
-Cl
C.
-OCH₃
D.
-NO₂
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ANSWER :
C. -OCH₃
17.
Picric acid is:
A.
2,4,6-Trichlorophenol
B.
2,4,6-Trinitrobenzoic acid
C.
2,4,6-Trinitrotoluene
D.
2,4,6-Trinitrophenol
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ANSWER :
D. 2,4,6-Trinitrophenol
18.
Why does a nitro group at para position increase the acidity of phenol significantly?
A.
It increases the bond strength of O-H bond
B.
It increases molecular weight
C.
It withdraws electrons by both -I and -M effects, stabilizing phenoxide
D.
It donates electrons to oxygen via resonance
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ANSWER :
C. It withdraws electrons by both -I and -M effects, stabilizing phenoxide