11. Which of the following compounds is the least reactive towards nucleophilic addition reactions?
a) Formaldehyde
b) Acetaldehyde
c) Acetone
d) Benzaldehyde
Answer: d) Benzaldehyde
Explanation: Benzaldehyde is less reactive than aliphatic aldehydes and ketones due to the electron-withdrawing nature of the benzene ring, which decreases the electrophilicity of the carbonyl carbon.
12. Which of the following carboxylic acids is the strongest acid?
a) Formic acid
b) Acetic acid
c) Benzoic acid
d) Chloroacetic acid
Answer: d) Chloroacetic acid
Explanation: Chloroacetic acid is the strongest acid due to the electron-withdrawing effect of the chlorine atom, which stabilizes the negative charge on the conjugate base.
13. Which of the following compounds will not undergo the Cannizzaro reaction?
a) Formaldehyde
b) Acetaldehyde
c) Benzaldehyde
d) Trimethylacetaldehyde
Answer: b) Acetaldehyde
Explanation: The Cannizzaro reaction occurs with aldehydes that lack alpha-hydrogens. Acetaldehyde has an alpha-hydrogen, so it undergoes aldol condensation rather than the Cannizzaro reaction.
14. Which of the following is the correct order of acidity?
a) Formic acid > Acetic acid > Benzoic acid
b) Benzoic acid > Formic acid > Acetic acid
c) Formic acid > Benzoic acid > Acetic acid
d) Acetic acid > Formic acid > Benzoic acid
Answer: c) Formic acid > Benzoic acid > Acetic acid
Explanation: Formic acid is more acidic than both acetic acid and benzoic acid due to the absence of electron-donating alkyl or phenyl groups. Benzoic acid is more acidic than acetic acid due to the electron-withdrawing effect of the phenyl group.
15. Aldol condensation involves the reaction between:
a) Two ketones
b) Two aldehydes
c) An aldehyde and a ketone
d) All of the above
Answer: d) All of the above
Explanation: Aldol condensation involves compounds that have alpha-hydrogens. Both aldehydes and ketones can undergo aldol condensation, either with themselves or with each other.
16. Which of the following compounds does not undergo aldol condensation?
a) Formaldehyde
b) Acetaldehyde
c) Acetone
d) Benzaldehyde
Answer: a) Formaldehyde
Explanation: Formaldehyde lacks alpha-hydrogens, which are necessary for aldol condensation to occur.
17. Which reagent is used for the decarboxylation of carboxylic acids?
a) NaOH and CaO
b) LiAlH₄
c) KMnO₄
d) PCC
Answer: a) NaOH and CaO
Explanation: Decarboxylation of carboxylic acids is typically carried out using soda lime (a mixture of NaOH and CaO), which removes the carboxyl group as carbon dioxide.
18. Which of the following is the most reactive toward nucleophilic acyl substitution?
a) Acetic acid
b) Acetyl chloride
c) Acetic anhydride
d) Methyl acetate
Answer: b) Acetyl chloride
Explanation: Acetyl chloride is the most reactive towards nucleophilic acyl substitution due to the presence of the highly electronegative chlorine atom, which makes the carbonyl carbon more electrophilic.
19. Which of the following carboxylic acids undergoes decarboxylation most easily?
a) Oxalic acid
b) Malonic acid
c) Succinic acid
d) Glutaric acid
Answer: b) Malonic acid
Explanation: Malonic acid undergoes decarboxylation easily because the product, acetic acid, is stabilized by resonance.
20. Which of the following reactions is used to prepare carboxylic acids from alkyl halides?
a) Grignard reaction
b) Kolbe’s reaction
c) Wurtz reaction
d) Finkelstein reaction
Answer: b) Kolbe’s reaction
Explanation: In Kolbe’s reaction, an alkyl halide reacts with carbon dioxide in the presence of a base to form a carboxylate ion, which is then protonated to give a carboxylic acid.
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