Here below some basic MCQ’s about “Amines and Nitro Compounds” with answer which is well explained for exam practice. Let’s check one by one which is given below.
1. Which of the following is the most basic amine?
a) Aniline
b) Methylamine
c) Diphenylamine
d) p-Nitroaniline
Answer: b) Methylamine
Explanation: Methylamine (CH₃NH₂) is a simple aliphatic amine, and aliphatic amines are generally more basic than aromatic amines because the lone pair on nitrogen is more readily available for protonation. In aniline, for example, the lone pair is delocalized into the benzene ring, reducing its basicity. Nitro groups (in p-Nitroaniline) also reduce the basicity by withdrawing electron density.
2. Which of the following will not undergo the Hoffmann bromamide reaction?
a) Methylamine
b) Benzylamine
c) Acetamide
d) Benzenesulfonamide
Answer: d) Benzenesulfonamide
Explanation: The Hoffmann bromamide reaction involves the conversion of an amide to a primary amine. Benzenesulfonamide is not an amide; it is a sulfonamide and thus will not undergo the Hoffmann reaction.
3. Which of the following reagents is used to distinguish between primary, secondary, and tertiary amines?
a) Carbylamine test
b) Lucas test
c) Hinsberg’s reagent
d) Tollens’ reagent
Answer: c) Hinsberg’s reagent
Explanation: Hinsberg’s reagent (benzenesulfonyl chloride, C₆H₅SO₂Cl) is used to distinguish between primary, secondary, and tertiary amines. Primary amines form a sulfonamide that is soluble in alkali, secondary amines form a sulfonamide that is insoluble in alkali, and tertiary amines do not react with Hinsberg’s reagent.
4. The nitro group (-NO₂) is a:
a) Strongly electron-donating group
b) Weakly electron-donating group
c) Weakly electron-withdrawing group
d) Strongly electron-withdrawing group
Answer: d) Strongly electron-withdrawing group
Explanation: The nitro group (-NO₂) is a strongly electron-withdrawing group due to the high electronegativity of nitrogen and oxygen, and the resonance effect, where the negative charge is delocalized over oxygen atoms. This reduces electron density on the rest of the molecule.
5. Aniline reacts with bromine water to give:
a) Mono-bromoaniline
b) Di-bromoaniline
c) Tri-bromoaniline
d) Tetra-bromoaniline
Answer: c) Tri-bromoaniline
Explanation: Aniline, due to the strongly activating nature of the amine group, reacts with bromine water to give 2,4,6-tribromoaniline, where bromine is substituted at the ortho and para positions of the benzene ring.
6. Which of the following compounds is formed when nitrobenzene is reduced with tin and hydrochloric acid?
a) Aniline
b) Benzylamine
c) Phenol
d) Benzene
Answer: a) Aniline
Explanation: Nitrobenzene (C₆H₅NO₂) is reduced to aniline (C₆H₅NH₂) when treated with reducing agents like tin (Sn) and hydrochloric acid (HCl). This is a standard reduction of the nitro group to the amino group.
7. Which of the following compounds can be prepared by the Gabriel phthalimide synthesis?
a) Methylamine
b) Aniline
c) Ethylamine
d) Both a and c
Answer: d) Both a and c
Explanation: Gabriel phthalimide synthesis is used to prepare primary aliphatic amines such as methylamine (CH₃NH₂) and ethylamine (C₂H₅NH₂). Aromatic amines like aniline cannot be synthesized by this method.
8. Which of the following is a method for converting an amide to an amine?
a) Hoffmann bromamide reaction
b) Gabriel synthesis
c) Sandmeyer reaction
d) Wurtz reaction
Answer: a) Hoffmann bromamide reaction
Explanation: The Hoffmann bromamide reaction converts an amide (RCONH₂) to a primary amine (RNH₂) by treating it with bromine (Br₂) and sodium hydroxide (NaOH).
9. The reduction of nitrobenzene in acidic medium produces:
a) Phenol
b) Aniline
c) Hydrazobenzene
d) Nitroethane
Answer: b) Aniline
Explanation: Reduction of nitrobenzene (C₆H₅NO₂) in an acidic medium (e.g., using Sn/HCl) results in the formation of aniline (C₆H₅NH₂), a primary aromatic amine.
10. Which of the following is NOT true about nitro compounds?
a) Nitro compounds are highly polar
b) Nitro compounds are generally insoluble in water
c) Nitro compounds show strong hydrogen bonding
d) Nitro compounds undergo reduction easily
Answer: c) Nitro compounds show strong hydrogen bonding
Explanation: Nitro compounds are polar due to the presence of the nitro group, but they do not exhibit strong hydrogen bonding because they lack a hydrogen atom attached to oxygen or nitrogen that could participate in hydrogen bonding. They are often insoluble in water and can undergo reduction reactions.
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