Amines Classification Questions and Answers

This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Amines Classification”.

1. When two alkyl groups are attached to the nitrogen atom in an amine, it is known as a _______ amine.
a) primary
b) secondary
c) tertiary
d) aromatic
View Answer

Answer: b
Explanation: Amines are classified as secondary or 2° when two of the hydrogen atoms of ammonia are replaced by an alkyl group and the third H remains attached as it is.

2. When only two hydrogen atoms are attached to the nitrogen of an amine, it is classified as a ________
amine.
a) primary
b) secondary
c) aliphatic
d) aromatic
View Answer

Answer: a
Explanation: When an amine has two hydrogen atoms individually bonded to the nitrogen, it means that the third group is an alkyl or aryl substituent. This is called as a primary or 1° amine as only one H atom is replaced.

3. Which of the following is not a classification of amines?
a) Primary
b) Secondary
c) Tertiary
d) Quaternary
View Answer

Answer: d
Explanation: Amines may be classified as primary, secondary or tertiary depending on whether 1, 2 or 3 hydrogen atoms of NH3 are replaced by alkyl/aryl groups respectively. Quaternary ammonium compounds are a different class of compounds where all four hydrogen atoms of ammonium salts are replaced by alkyl/aryl groups.

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4. What is the most suitable classification of the following amine?

a) Secondary amine
b) Dialkyl amine
c) Tertiary amine
d) Aromatic amine
View Answer

Answer: c
Explanation: This is trimethylamine, in which all the three hydrogen atoms are replaced by methyl (CH₃) groups. Hence, it is a tertiary or 3° amine.

5. Which of the following is a 2° amine?
a) CH₃CH₂NHCH₃
b) (CH₃)₃N
c) (CH₃CH₂CH₂)₂NCH₃
d) C₆H₅NH₂
View Answer

Answer: a
Explanation: The three groups attached to CH₃CH₂NHCH₃ are one methyl group, one ethyl group and one hydrogen atom. This means that two of the hydrogen atoms are replaced and hence, it is a 2° or secondary amine.

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6. Benzylamine is an aryl amine.
a) True
b) False
View Answer

Answer: b
Explanation: Aryl amines are aromatic amines in which the nitrogen atom is directly bonded to the benzene ring. Whereas in benzylamine (C₆H₅CH₂NH₂), the nitrogen is attached to the side chain of the aromatic ring. Hence, it is an arylalkyl amine.

7. Which of the following is the most suitable classification for C₆H₅NHCH₃?
a) Tertiary amine
b) Aliphatic amine
c) Arylalkyl amine
d) Mixed amine
View Answer

Answer: d
Explanation: In the given amine, there are two substituents, one methyl group and one phenyl group. Hence, it is a secondary aryl amine and since both the substituent groups are different, it is a mixed amine.

8. Which of the following is an arylalkyl amine?
a) C₆H₅NHC₆H₅
b) C₆H₅NH₂
c) (C₆H₅CH₂)NH
d) (C₆H₅)₃N
View Answer

Answer: c
Explanation: Arylalkyl amines are aromatic amines which are side chain substituted, i.e., the nitrogen is not directly attached to the phenyl group but to a side chain of the benzene ring. In (C₆H₅CH₂)NH, there are two same groups attached to the nitrogen where it is attached to a benzyl carbon, instead of an aryl carbon.

9. Which of the following categories does CH₃-NH-CH₃ not belong to?
a) Secondary amine
b) Simple amine
c) Aliphatic amine
d) Mixed amine
View Answer

Answer: d
Explanation: There are two hydrogen that replaced by CH₃ group, making it a secondary amine and since both the replacing groups are identical, it is a simple amine. Also, it is aliphatic in nature as both the substituents are alkyl groups.

10. Aromatic amines cannot have an alkyl group attached to N atom.
a) True
b) False
View Answer

Answer: b
Explanation: There can be an alkyl group attached to an aromatic amine, but at least one of the substituents should be a phenyl group in aryl amine. For arylalkyl amines (which are also aromatic), the benzene ring is not directly linked to the nitrogen.

11. (C₃H₇)N(CH₃)(C₂H₅) is not a ________ amine.
a) secondary
b) tertiary
c) aliphatic
d) mixed
View Answer

Answer: a
Explanation: In the given amine, all the three hydrogens of NH₃ are replaced by one each of propyl, ethyl and methyl groups, and is a tertiary or 3° amine. Since all the three groups are alkyl and different, it is an aliphatic mixed amine.

12. The compound shown is a _______ amine.

a) 1° aryl
b) 1° arylalkyl
c) 2° aryl
d) 2° arylalkyl
View Answer

Answer: a
Explanation: Only one hydrogen atom is replaced by an aromatic group, in which the nitrogen is directly linked to the sp² hybridised carbon of benzene ring. Hence, it is a primary aromatic aryl amine.

13. Which of the following best describes the amine (CH₃CH₂)₃N?
a) Secondary, simple
b) Secondary, mixed
c) Tertiary, simple
d) Tertiary, mixed
View Answer

Answer: c
Explanation: All the three hydrogen atoms of ammonia are replaced by the same ethyl group in (CH₃CH₂)₃N, which makes is a 3° simple amine.

14. Which of the following is a primary arylalkyl amine?
a) CH₃NH₂
b) C₆H₅CH₂NH₂
c) C₆H₅NH₂
d) (C₆H₅)₂NH
View Answer

Answer: b
Explanation: Since it should be primary, it should have an alkyl/aryl group attached to the NH₂ molecule, and because it is arylalkyl, the nitrogen should be linked to an sp³ hybridised benzyl carbon rather than to an aryl carbon.

15. The compound CH₃NHC₆H₅ is a ______ amine.
a) aliphatic simple
b) aliphatic mixed
c) aromatic simple
d) aromatic mixed
View Answer

Answer: d
Explanation: Since the compound consists of a benzene ring, it invariably is an aromatic amine. Moreover, it also contains an alkyl methyl group beside the phenyl group and this makes it a mixed amine.

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