Important Questions for CBSE Class 12 Chemistry – Organic Compounds Containing Nitrogen (Amines)

  

Important Questions for CBSE Class 12 Chemistry – ORGANIC COMPOUNDS CONTAINING NITROGEN (AMINES)

PREVIOUS YEARS QUESTIONS

2015 – Short Answer Type Questions [I] [2 Marks]

Question 1:
Arrange the following in increasing order of their basic strengths:

Answer:

Question 2:
Arrange the following in increasing order of their basic strengths.

Answer:

Question 3:

Answer:

Short Answer Type Questions [II] [3 Marks]

Question 4:
How can the following conversions be carried out
(i) Aniline to bromobenzene
(ii) Chlorobenzene to 2-chloroacetephenane
(iii) Chloroethane to butane.
Answer:

Question 5:

Answer:

Question 6:

Answer:

Question 7:
Give Reasons for the following:

1. Aniline does not undergo Friedel-Crafts reaction.
2. þ methylaniline is more basic than þ nitroaniline.
3. Acetylation of —NH2 group is done in aniline before preparing its ortho and para compounds.

Answer:
It is because C6H5NH2 is basic, reacts with Lewis acid A1C13 to form salt. It is because methyl group is electron releasing, whereas nitrogroup is electron withdrawing.
It is done so as to decrease the reactivity of Aniline towards electrophilic substitution reactions.

Long Answer Type Questions [5 Marks]

Question 8:


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Question 9:

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Question 10:

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Question 11:

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Question 12 :

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Question 13:

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Question 14:

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Question 15:

Answer:

 

2014 – Very Short Answer Type Questions [1 Mark]

Question 16:

Answer:
CgH5NH2 < (C2H5)2NH < C2H5NH2 is the increasing order of solubility in water.

Question 17:

Answer:

Question 18:

Answer:

Question 19:
The conversion of primary aromatic amines into diazonium salts is known
as——–
Answer:
Diazotization.

Question 20:
Which of the two is more basic and why?

Answer:

Question 21:
Write the IUPC name of the compound :

Answer 
2-Hydroxy benzaldehyde.

Question 22:

Answer:
CH3—NH2 has higher boiling point.

Question 23:
Which of the two is more basic and why?
CH3NH2 or NHg
Answer:
H3NH2 is more basic because CH3_ group is electron releasing, increases electron density on ‘N’.

Question 24:

Which of the two is  more basic and why?

Answer:

Short Answer Type Question [I][2 Marks]

Question 25:
Distinguish between the following pairs by suitable chemical test:

1. Aniline and ethyl amine
2. Aniline and Benzyl amine

Answer:

1.  On adding benzene diazonium chloride, aniline forms yellow azo dye, whereas ethyl amine does not.
2. On adding benzene diazonium chloride, aniline forms yellow azo dye, whereas benzyl amine does not.

 

Short Answer Type Question [I][3 Marks]

Question 26:

Answer:

Question 27:
How will you convert the following
(i) Nitrobenzene into aniline
(ii) Ethanoic acid into methanamine
(iii) Aniline into N-phenylethanamide
(Write the chemical equations involved.)
Answer:

Question 28:

Answer:

Question 29:

Answer:

Very Short Answer Type Question [I Mark]

Question 30:
Arrange the following in increasing order of their basic strength in aqueous solution:
CH3NH2, (CH3)3N, (CH3)2NH
Answer:
(CH3)3N < CH3NH2 < (CH3)2NH

Question 31:
Write the structure of N-methylethanamine.
Answer:
CH3CH2NHCH3

Question 32:
Why is methylamine more basic than aniline?
Answer:
Because of +ve charge on ‘N’ in 3 out of 5 resonating structures of aniline, aniline is less basic than methylamine in which —CH3 group is an electron releasing and electron density on ‘N’ is higher.

Question 33:
Ethylamine is soluble in water, whereas aniline is almost insoluble, why?
Answer:
It is because ethyl amine can form H-bonds with water whereas aniline cannot form H-bonds.

Question 34:
Why are diazonium salts of aromatic amines more stable than those of aliphatic amines?
Answer:
It is because benzene diazonium ion is stabilized by resonance.

Short Answer Type Questions [II][3 Marks]

Question 35:

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Question 36:

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Question 37:

Answer:

 

Question 38:

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Question 39:

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Question 40:

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Question 41:

Answer:

Question 42:
How are the following conversions carried out:
(i) Aniline to Iodobenzene
(ii) Ethyl nitrile to Ethyl amide
(iii) Benzene diazonium chloride to Benzonitrile
Answer:

Very Short Answer Type Questions [1 Mark]

Question 43:
Arrange the following compounds in an increasing order of basic strengths in their aqueous solutions:
NH3, CH3NH2, (CH3)2NH, (CH3)3N
Answer:
(CH3)2NH > CH3NH2 > (CH3)3N > NH3.

Short Answer Type Questions [I][2 Marks]

Question 44:
Describe the following giving the relevant chemical equation in each case:
(i) Carbylamine reaction
(ii) Hoffmann’s bromamide reaction.
Answer:

Question 45:

Answer:

Short Answer Type Questions[II] [2 Marks]

Question 46:
Write chemical equations for the following conversions:
(i) Nitrobenzene to benzoic acid.
(ii) Benzyl chloride to 2-phenylethanamine.
(iii) Aniline to benzyl-alcohol.
Answer :

Very Short Answer Type Questions [1 Mark] 

Question 47:
Why is an alkylamine more basic than ammonia?
Answer:
It is because alkyl groups are electron releasing. In alkyl amines, they will increase electron density on ‘N’, therefore, they are more basic than NH3.

Question 48:
Write one reaction that can be used as a test for primary amines.
Answer:
RNH2 + CHC13 + 3KOH > R—N^C+ 3KC1 + 3H20 is used as a test for primary amine.

Question 49:
Arrange the following compounds in an increasing order of their solubility in water: C6H5NH2, (C2H5)2NH, C2HgNH2
Answer:
C6H5NH2 < (C2H5)2NH < C2H5NH2

Question 50:
Rearrange the following in an increasing order of their basic strengths:
Answer:
C6H5NH2, C6H5N(CH3)2, (C6H5)NH and CH3NH2

Question 51 :
Give a chemical test to distinguish between ethylamine and aniline.
Answer:
Add NaN02 and HC1. Cool it to 0-5 °C. Add alkaline solution of phenol. Orange dye will be formed in case of aniline but not in the case of ethyl amine.

Question 52:
How will you bring about the following conversions:
(i) Nitrobenzene to Phenol
(ii) Aniline to Chlorobenzne
Answer:

Question 53:
How will you bring about the following conversions:
(i) Ethanamine to Ethanoic acid (ii) Aniline to Benzonitrile
Answer:

Question 54:
Illustrate the following reactions giving a chemical equation in each case:
(i) Gabriel phthalimide synthesis (ii) A coupling reaction
(ii) Hoffmann’s bromamide reaction.
Answer:
(i) Refer Ans. to Q. 14 (a) (ii)
(ii) Refer Ans. to Q.12 (a) (ii)
(iii) Refer Ans. to Q.44 (ii)

Question 55:
(a) Explain why an alkylamine is more basic than ammonia.
(b) How would you convert
(i) Aniline to nitrobenzene?
(ii) Aniline to iodobenzene?
Answer:

Question 56:

Answer:

Question 57:
State reasons for the following:

1.  pKb value for aniline is more than that for methylamine.
2. Ethylamine is soluble in water whereas aniline is not soluble in water,
3. Primary amines have higher boiling points than tertiary amines.

Answer:

1.  It is because aniline is less basic than methyl amine due to presence of electron withdrawing phenyl group, it has more pKb
2.  Refer Ans. to Q.33.
3. Refer Ans. to Q.28 (i).

2010 – A Very Short Answer Type Question [1 Mark]

Question 58:
Give the IUPAC name of
H2N—CH2—CH2—CH=CH2.
Answer:
But-3-en-l-amine.

Short Answer Type Questions [I] [2 Marks]

Question 59:
Write one chemical reaction each to illustrate the following:
(i) Acetylation (ii) Gabriel Phthalimide synthesis
Answer:

Question 60:

Answer:

 

Question 61:

Answer:

Question 62:
Give the chemical test to distinguish between the following pairs of compounds:

1.  Ethylamine and Aniline
2.  Aniline and Benzylamine

Answer:

1. Refer Ans. to Q.25 (i)
2.  Add Br2 water. Aniline will form white precipitate whereas benzylamine will not form white precipitate.

Question 63:
Give the chemical test to distinguish between the following pairs of compounds:

1.  Methylamine and Dimethylamine
2. Aniline and N-methylaniline

Answer :

1.  Add CHC13 and KOH. Methylamine will form offensive smelling compound, dimethylamine will not react.
2. Add CHC13 and KOH. Aniline will form foul smelling compound, N-methylaniline will not.

Question 65:
Explain the following giving a reason in each case

1. Why is an alkylamine more basic than ammonia?
2. Why do primary amines have higher boiling points than the tertiary amines?

Answer :

1.  Refer Ans. to Q.55 (a)
2.  Refer Ans. to Q.28 (i).

Question 65:

Answer:

Question 66:

Answer:

2009  – Very Short Answer Type Question [1 Mark]

Question 67:
Why is an alkylamine more basic than ammononia?
Answer:
Refer Ans. to Q.55 (a)
Question 68:

Arrange the following compounds in an increasing order of basic strengths in their aqueous solations
NH3, CH3NH2, (CH3)2NH, (CH3)3N
Answer:
NH3 < (CH3)3N < CH3NH2 < (CH3)2NH
Question 69:
Arrange the following compounds in an increasing order of their basic strength in aqueous solution
NH3, RNH2, RJJNH, R3N
Answer:
NH3 < R3N < RNH2 < R2NH

Question 70:
Give an example for each describe the following reactions (i) Hoffmann’s bromide reaction (ii) Gattermann reaction (in) A coupling reaction
Answer:
(i) Refer Ans. to Q.14

Question 72:

Answer:

Question 73:

Answer :

Question 74:
How are the following conversions carried out?
(i) Aniline to nitrobenzene (ii) Ethanamine to N-ethylethanamide (iii) Chloroethane to propan-1-amine
Answer :