91. Which of the following reagents is used in the Wolff-Kishner reduction?
a) H₂SO₄
b) Hydrazine
c) Zinc amalgam
d) PCC
Answer: b) Hydrazine
Explanation: The Wolff-Kishner reduction involves the conversion of a ketone or aldehyde into an alkane using hydrazine (NH₂NH₂) in basic conditions.
92. The reaction of benzaldehyde with sodium hydroxide (NaOH) produces:
a) Benzoic acid
b) Benzyl alcohol
c) Benzoin
d) Benzaldehyde and benzoic acid
Answer: d) Benzaldehyde and benzoic acid
Explanation: In the Cannizzaro reaction, two molecules of benzaldehyde react with sodium hydroxide. One is oxidized to benzoic acid, and the other is reduced to benzyl alcohol.
93. Which of the following reagents will convert acetone into a secondary alcohol?
a) NaBH₄
b) H₂O₂
c) KMnO₄
d) Br₂
Answer: a) NaBH₄
Explanation: Sodium borohydride (NaBH₄) is a reducing agent that converts ketones like acetone into secondary alcohols.
94. Which of the following acids is the most acidic?
a) Formic acid
b) Acetic acid
c) Propanoic acid
d) Butanoic acid
Answer: a) Formic acid
Explanation: Formic acid (HCOOH) is more acidic than acetic acid and other higher carboxylic acids because it lacks alkyl groups that would reduce the acidity by donating electron density.
95. Which of the following is not an intermediate in the aldol condensation reaction?
a) Enolate ion
b) Aldehyde
c) Ketone
d) Alkane
Answer: d) Alkane
Explanation: In an aldol condensation, an enolate ion reacts with an aldehyde or ketone, but alkanes are not involved in the reaction mechanism.
96. The Perkin reaction is used to synthesize:
a) Esters
b) Aldehydes
c) Alpha, beta-unsaturated acids
d) Amines
Answer: c) Alpha, beta-unsaturated acids
Explanation: The Perkin reaction is a method for synthesizing alpha, beta-unsaturated acids by condensing an aromatic aldehyde with an acid anhydride.
97. Which of the following reagents is used to selectively reduce an aldehyde to a primary alcohol?
a) H₂SO₄
b) NaBH₄
c) CrO₃
d) NaOH
Answer: b) NaBH₄
Explanation: Sodium borohydride (NaBH₄) is a selective reducing agent that converts aldehydes into primary alcohols without affecting other functional groups.
98. Which of the following statements is correct about ketones?
a) Ketones can be reduced to primary alcohols
b) Ketones can be reduced to secondary alcohols
c) Ketones are oxidized to aldehydes
d) Ketones undergo reduction with KMnO₄
Answer: b) Ketones can be reduced to secondary alcohols
Explanation: Ketones are reduced to secondary alcohols using reducing agents like NaBH₄ or LiAlH₄.
99. Which of the following compounds will react with sodium bicarbonate (NaHCO₃)?
a) Ethanol
b) Acetic acid
c) Acetone
d) Ethyl acetate
Answer: b) Acetic acid
Explanation: Acetic acid reacts with sodium bicarbonate to form carbon dioxide (CO₂), water, and sodium acetate. Only acids react with NaHCO₃.
100. Which of the following aldehydes undergoes the Cannizzaro reaction?
a) Acetaldehyde
b) Benzaldehyde
c) Propanal
d) Butanal
Answer: b) Benzaldehyde
Explanation: Benzaldehyde undergoes the Cannizzaro reaction because it lacks alpha-hydrogens, making it suitable for this disproportionation reaction.
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