CHEMISTRY WORKSHEET

Chapter: Amines
Class XII | Time: 3 Hours | Maximum Marks: 70

GENERAL INSTRUCTIONS:

1. All questions are compulsory.

2. Section A contains 16 questions (12 MCQs + 4 Assertion-Reason) of 1 mark each.
3. Section B contains 5 questions of 2 marks each.
4. Section C contains 7 questions of 3 marks each.
5. Section D contains 2 case-based questions of 4 marks each.
6. Section E contains 3 questions of 5 marks each.
7. There is no overall choice. However, internal choices have been provided in some questions.

SECTION A (16 × 1 = 16 marks)

Multiple Choice Questions (1-12)

1. The IUPAC name of (CH₃)₂CHNH₂ is:

(a) Isopropylamine (b) Propan-2-amine (c) N-methylethanamine (d) 2-Aminopropane

2. Which of the following is the strongest base?

(a) NH₃ (b) CH₃NH₂ (c) (CH₃)₂NH (d) (CH₃)₃N

3. Aniline does not undergo Friedel-Crafts reaction because:

(a) It is a weak base (b) It forms salt with AlCl₃

(c) Benzene ring is deactivated (d) Both (b) and (c)

4. The reagent used to distinguish between primary, secondary and tertiary amines is:

(a) NaNO₂ + HCl (b) CHCl₃ + KOH (c) Hinsberg reagent (d) Lucas reagent

5. Benzene diazonium chloride on treatment with CuCl/HCl gives:

(a) Chlorobenzene (b) Benzonitrile (c) Phenol (d) Aniline

6. Gabriel phthalimide synthesis is used for the preparation of:

(a) Primary amines (b) Secondary amines

(c) Tertiary amines (d) Quaternary ammonium salts

7. The hybridization of nitrogen atom in amines is:

(a) sp (b) sp² (c) sp³ (d) sp³d

8. Which of the following amines has the highest boiling point?

(a) CH₃NH₂ (b) (CH₃)₂NH (c) (CH₃)₃N (d) C₂H₅NH₂

9. Diazonium salts are stable at:

(a) Room temperature (b) 0-5°C (c) 100°C (d) Any temperature

10. The reaction of aniline with bromine water gives:

(a) 2-Bromoaniline (b) 3-Bromoaniline (c) 4-Bromoaniline (d) 2,4,6-Tribromoaniline

11. Which of the following gives positive carbylamine test?

(a) (CH₃)₂NH (b) (CH₃)₃N (c) CH₃NH₂ (d) C₆H₅NHCH3

12. Hoffmann bromamide degradation of benzamide gives:

(a) Benzylamine (b) Aniline (c) N-methylaniline (d) Benzonitrile

Assertion-Reason Questions (13-16)

Instructions: In the following questions, a statement of assertion (A) is followed by a statement of reason
(R). Choose the correct answer from the options given below:

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

13. Assertion (A): Aliphatic amines are stronger bases than aromatic amines.

Reason (R): In aromatic amines, lone pair of electrons on nitrogen is delocalized over the benzene ring.

14. Assertion (A): Primary amines have higher boiling points than tertiary amines.

Reason (R): Primary amines form stronger hydrogen bonds than tertiary amines.

15. Assertion (A): Aniline gives white precipitate with bromine water.

Reason (R): Bromine water acts as an oxidizing agent.

16. Assertion (A): Diazonium salts cannot be isolated in dry state.

Reason (R): Diazonium salts are explosive in nature when dry.

SECTION B (5 × 2 = 10 marks)
17. Classify the following amines as primary, secondary or tertiary: (a) CH₃NHCH₂CH₃ (b) (CH₃CH₂)₃N (c)
CH₃CH₂CH₂NH₂ (d) (CH₃)₂NCH₂CH₃

18. Write the structures of the following compounds: (a) N,N-diethylaniline (b) 2-Methylpropan-2-amine
19. How will you convert: (a) Aniline to phenol (b) Aniline to chlorobenzene

20. What happens when: (a) Ethylamine reacts with nitrous acid (b) Aniline is treated with bromine in CS₂

21. Arrange the following in increasing order of basic strength: NH₃, CH₃NH₂, (CH₃)₂NH, C₆H₅NH₂

SECTION C (7 × 3 = 21 marks)
22. Describe the preparation of aniline from: (a) Nitrobenzene (b) Benzamide (c) Phenol

23. How will you distinguish between the following pairs? Give chemical tests: (a) Methylamine and
dimethylamine (b) Aniline and N-methylaniline (c) Ethylamine and diethylamine

24. Explain the following observations: (a) Aniline does not give Friedel-Crafts acylation (b) Primary
amines have higher boiling points than tertiary amines (c) Aniline is a weaker base than methylamine

25. Write the chemical equations for the following reactions: (a) Reduction of nitrobenzene with Fe/HCl (b)
Diazotization of aniline(Preparation of Benzene Diazonium Chloride) (c) Sandmeyer reaction of benzene
diazonium chloride with CuBr/HBr

26. Describe the preparation of primary amines by: (a) Gabriel phthalimide synthesis (b) Reduction of
nitriles (c) Reduction of amides

27. How will you bring about the following conversions: (a) Nitrobenzene to aniline (b) Aniline to
iodobenzene (c) Benzene to aniline

28. Account for the following: (a) Aliphatic amines are stronger bases than aromatic amines (b) Ethylamine
is more soluble in water than aniline

SECTION D (2 × 4 = 8 marks)
29. Case Study 1: A student was given four organic compounds A, B, C, and D, all having molecular
formula C₇H₉N. The student performed the following tests:

Compound A: Gives positive carbylamine test, forms diazonium salt with NaNO₂/HCl at 0-5°C Compound
B: Gives negative carbylamine test, gives yellow oily layer with NaNO₂/HCl Compound C: Does not react
with NaNO₂/HCl, gives positive carbylamine test

(a) Identify the nature (1°, 2°, or 3°) of compounds A, B, C. (2 marks)

(b) Which compound will be most basic? Justify your answer. (1 mark)

(c) Write the structure of compound A and name the test used to distinguish between A and B. (1 mark)

30. Case Study 2: Diazonium salts are versatile intermediates in organic synthesis. They undergo various
reactions to form different classes of compounds. The following reactions show the synthetic utility of
benzene diazonium chloride:

C₆H₅N₂⁺Cl⁻ --[X]--> C₆H₅Cl C₆H₅N₂⁺Cl⁻ --[Y]--> C₆H₅OH

C₆H₅N₂⁺Cl⁻ --[Z]--> C₆H₅CN

(a) Identify reagents X, Y, and Z. (2 marks)

(b) Why are diazonium salts kept at low temperature? (1 mark)

(c) Name the reaction when benzene diazonium chloride is treated with Aniline in alkaline medium. (1
mark)

SECTION E (3 × 5 = 15 marks)
31. (a) Describe the preparation of aniline from nitrobenzene. Write the reaction. (3 marks)
(b) How will you distinguish between primary, secondary and tertiary amines using Hinsberg reagent?
(2 marks)

OR

(a) Explain Gabriel phthalimide synthesis for the preparation of primary amines. Write the complete reaction
mechanism. (3 marks)
(b) Why cannot this method be used for the preparation of aniline? (2 marks)

32. (a) Explain the basic nature of amines. Why are aliphatic amines stronger bases than aromatic amines?
(3 marks)
(b) Arrange the following in increasing order of basic strength and justify: (2 marks)

C₆H₅NH₂, (C₂H₅)₂NH, C₂H₅NH₂, NH₃

OR

(a) Discuss the structure of amines. How does hydrogen bonding affect their physical properties? (3 marks)
(b) Explain why tertiary amines have lower boiling points than primary amines of comparable molecular
mass. (2 marks)

33. (a) Write the preparation, properties and uses of diazonium salts. (3 marks)
(b) Complete the following reactions: (2 marks)

 C₆H₅N₂⁺Cl⁻ + KI → ?
 C₆H₅N₂⁺Cl⁻ + H₃PO₂ + H₂O → ?

OR

(a) Describe the importance of diazonium salts in synthetic organic chemistry with examples. (3 marks)
(b) How will you prepare the following from aniline? (2 marks)

i. Fluorobenzene
ii. Benzene