51. What happens when nitrobenzene is reduced using Zn/NaOH?
a) Aniline is formed
b) Phenylhydroxylamine is formed
c) Benzylamine is formed
d) Nitrobenzene is converted into azobenzene
Answer: b) Phenylhydroxylamine is formed
Explanation: When nitrobenzene (C₆H₅NO₂) is reduced using zinc and sodium hydroxide (Zn/NaOH), phenylhydroxylamine (C₆H₅NHOH) is formed as the intermediate product.
52. Which of the following reagents can convert a nitro group into an amino group?
a) NaBH₄
b) H₂/Pd
c) KMnO₄
d) Na₂SO₄
Answer: b) H₂/Pd
Explanation: Hydrogen gas (H₂) in the presence of a palladium catalyst (Pd) can reduce a nitro group (-NO₂) to an amino group (-NH₂), converting nitrobenzene into aniline.
53. Which of the following is the correct order of basicity in the gas phase?
a) NH₃ > CH₃NH₂ > (CH₃)₂NH > (CH₃)₃N
b) (CH₃)₃N > (CH₃)₂NH > CH₃NH₂ > NH₃
c) (CH₃)₂NH > (CH₃)₃N > NH₃ > CH₃NH₂
d) NH₃ > (CH₃)₂NH > (CH₃)₃N > CH₃NH₂
Answer: b) (CH₃)₃N > (CH₃)₂NH > CH₃NH₂ > NH₃
Explanation: In the gas phase, the basicity of amines increases with the number of alkyl groups because alkyl groups donate electron density to the nitrogen atom, increasing its ability to accept a proton.
54. Aniline reacts with acetyl chloride to form:
a) Acetaldehyde
b) Acetamide
c) Acetanilide
d) Benzanilide
Answer: c) Acetanilide
Explanation: When aniline reacts with acetyl chloride (CH₃COCl), it undergoes acetylation to form acetanilide (C₆H₅NHCOCH₃). This reaction is commonly used to protect the amino group.
55. Which of the following is used in the nitration of benzene?
a) HCl and NaOH
b) HNO₃ and H₂SO₄
c) Br₂ and Fe
d) NaNO₂ and HCl
Answer: b) HNO₃ and H₂SO₄
Explanation: Nitration of benzene is carried out by treating it with a mixture of concentrated nitric acid (HNO₃) and sulfuric acid (H₂SO₄), which generates the nitronium ion (NO₂⁺) that acts as the electrophile.
56. Which of the following reactions is a nucleophilic substitution reaction?
a) Bromination of aniline
b) Diazotization of aniline
c) Conversion of benzyl chloride to benzylamine
d) Nitration of toluene
Answer: c) Conversion of benzyl chloride to benzylamine
Explanation: The conversion of benzyl chloride to benzylamine is a nucleophilic substitution reaction where the chloride ion (Cl⁻) is replaced by the amine group (-NH₂) through a nucleophilic attack.
57. Which of the following reactions does not involve an amine?
a) Gabriel phthalimide reaction
b) Sandmeyer reaction
c) Hoffmann rearrangement
d) Nitration of benzene
Answer: d) Nitration of benzene
Explanation: Nitration of benzene involves the introduction of a nitro group (-NO₂) onto a benzene ring using nitric acid and sulfuric acid, and it does not involve any amine compound.
58. Which reagent is used to convert aniline into iodobenzene?
a) I₂ and HNO₃
b) NaI and NaNO₂
c) KI and H₂SO₄
d) NaNO₂, HCl, and KI
Answer: d) NaNO₂, HCl, and KI
Explanation: Aniline is first diazotized with NaNO₂ and HCl to form the diazonium salt, which then reacts with potassium iodide (KI) to give iodobenzene (C₆H₅I).
59. Which of the following is most basic?
a) Aniline
b) p-Nitroaniline
c) m-Toluidine
d) Benzylamine
Answer: d) Benzylamine
Explanation: Benzylamine is more basic than aniline and its derivatives because the benzyl group (CH₂C₆H₅) does not significantly delocalize the nitrogen’s lone pair, making it more available for protonation compared to the aromatic amines.
60. What is the major product of the reaction of aniline with H₂SO₄ and HNO₃?
a) Nitrobenzene
b) p-Nitroaniline
c) o-Nitroaniline
d) m-Nitroaniline
Answer: b) p-Nitroaniline
Explanation: The nitration of aniline is controlled by the strong activating effect of the amino group (-NH₂), leading to substitution at the para position, resulting in p-nitroaniline as the major product.
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