chemistry : class12 Monoamines : Classification of amines : Organic Compounds Containing Nitrogen MCQ Questions and Answers
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Monoamines
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MCQ Questions
1. Which of the following compounds is a primary aromatic monoamine?
A.
Aniline, C6H5NH2
B.
N-Methylaniline, C6H5NHCH3
C.
Diphenylamine, (C6H5)2NH
D.
Trimethylamine, (CH3)3N
Correct Answer:
Aniline, C6H5NH2
Explanation:
Aniline contains one amino group directly attached to an aromatic ring, and its nitrogen is bonded to only one carbon group; therefore, it is a primary aromatic monoamine.
2. N-Ethylaniline, C6H5NHCH2CH3, is correctly classified as a:
A.
Primary aliphatic monoamine
B.
Secondary aromatic monoamine
C.
Tertiary aromatic monoamine
D.
Secondary aliphatic monoamine
Correct Answer:
Secondary aromatic monoamine
Explanation:
N-Ethylaniline has one nitrogen atom bearing two carbon groups, phenyl and ethyl, so it is secondary; because one carbon group is an aromatic ring, it is classified as an aromatic monoamine.
3. Which compound is a tertiary aromatic monoamine rather than a secondary aromatic monoamine?
A.
Aniline
B.
N-Methylaniline
C.
N,N-Dimethylaniline
D.
Benzylamine
Correct Answer:
N,N-Dimethylaniline
Explanation:
In N,N-dimethylaniline, nitrogen is bonded to a phenyl group and two methyl groups, making three carbon substituents; hence it is a tertiary aromatic monoamine.
4. Which of the following is classified as a primary aliphatic monoamine?
A.
Benzylamine, C6H5CH2NH2
B.
Aniline, C6H5NH2
C.
N-Methylaniline, C6H5NHCH3
D.
N,N-Dimethylaniline, C6H5N(CH3)2
Correct Answer:
Benzylamine, C6H5CH2NH2
Explanation:
In benzylamine, the nitrogen is attached to a carbon of the side chain rather than directly to the aromatic ring. It has one carbon substituent on nitrogen, so it is a primary aliphatic monoamine.
5. Which pair contains, respectively, a secondary aliphatic monoamine and a secondary aromatic monoamine?
A.
Diethylamine and N-methylaniline
B.
Aniline and diethylamine
C.
Triethylamine and aniline
D.
Benzylamine and trimethylamine
Correct Answer:
Diethylamine and N-methylaniline
Explanation:
Diethylamine has two alkyl groups attached to nitrogen and is a secondary aliphatic monoamine. N-Methylaniline has two carbon groups attached to nitrogen, including a phenyl group, and is a secondary aromatic monoamine.
6. A monoamine contains one nitrogen atom bonded to three carbon groups, two of which are methyl groups and one of which is phenyl. Its classification is:
A.
Primary aromatic monoamine
B.
Secondary aromatic monoamine
C.
Tertiary aromatic monoamine
D.
Tertiary aliphatic monoamine
Correct Answer:
Tertiary aromatic monoamine
Explanation:
The nitrogen is bonded to three carbon groups, establishing tertiary classification. Since one of those groups is phenyl, the compound is an aromatic monoamine.
7. Which structural description corresponds to a secondary aliphatic monoamine?
A.
Nitrogen bonded to one alkyl group and two hydrogen atoms
B.
Nitrogen bonded to two alkyl groups and one hydrogen atom
C.
Nitrogen bonded directly to one phenyl group and two hydrogen atoms
D.
Nitrogen bonded to three alkyl groups and no hydrogen atom
Correct Answer:
Nitrogen bonded to two alkyl groups and one hydrogen atom
Explanation:
A secondary monoamine has nitrogen bonded to two carbon groups and one hydrogen atom. When both carbon groups are alkyl groups, it is specifically a secondary aliphatic monoamine.
8. Which compound is incorrectly classified as a primary aromatic monoamine?
A.
Aniline, C6H5NH2
B.
p-Toluidine, CH3C6H4NH2
C.
Benzylamine, C6H5CH2NH2
D.
o-Toluidine, CH3C6H4NH2
Correct Answer:
Benzylamine, C6H5CH2NH2
Explanation:
Benzylamine is primary because nitrogen bears one carbon group, but the nitrogen is not directly attached to the aromatic ring. Therefore, it is a primary aliphatic rather than a primary aromatic monoamine.
9. Which sequence correctly classifies methylamine, dimethylamine, and trimethylamine in that order?
A.
Primary, secondary, tertiary aliphatic monoamines
B.
Primary, tertiary, secondary aliphatic monoamines
C.
Secondary, primary, tertiary aromatic monoamines
D.
Primary, secondary, tertiary aromatic monoamines
Explanation:
Methylamine has one methyl group on nitrogen, dimethylamine has two, and trimethylamine has three. All groups are alkyl groups, so their classifications are primary, secondary, and tertiary aliphatic monoamines, respectively.
10. Which option lists compounds in the order: primary aromatic monoamine, secondary aromatic monoamine, tertiary aromatic monoamine?
Explanation:
Aniline has one carbon group on nitrogen and is primary. N-Methylaniline has two and is secondary. N,N-Dimethylaniline has three and is tertiary; all are classified as aromatic monoamines because nitrogen is directly attached to a phenyl group.
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