All questions of Compounds Containing Nitrogen for JEE Exam

Statement - 1 :  In strongly acidic solutions, aniline becomes more reactive towards electrophilic reagents.
Statement-2 : The amino group being completely protonated in strongly acidic solution, the lone pair of electrons on the nitrogen is no longer available for resonance.
  • a)
    Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.
  • b)
    Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1
  • c)
    Statement-1 is True, Statement-2 is False
  • d)
    Statement-1 is False, Statement-2 is True
Correct answer is option 'D'. Can you explain this answer?

Krishna Iyer answered
TIPS/FORMULAE : Electron donating tendency to a double bond is called +M effect and the transfer of electrons take place towards the attacking reagent due to +E effect.
In strongly acidic conditions, aniline becomes protonated with the result lone pair of electrons is not available to produce +E and +M effects. Thus here aniline becomes less reactive towards electrophilic substitution. On the other hand, the   group exerts strong –I effect causing deactivation of the

p-Chloroaniline and anilinium hydrochloride can be distinguished by
  • a)
    Sandmeyer reaction
  • b)
    NaHCO3
  • c)
    AgNO3
  • d)
    Carbylamine test
Correct answer is option 'C'. Can you explain this answer?

Chirag Verma answered
TIPS/Formulae : Anilinium hydrochloride has ionisable chlorine whereas chlorobenze has non ionizable chlorine. Thus anilium hydrochloride gives white precipitate of AgCl with AgNO3.

In chloroaniline, –Cl is directly attached to benzene ring, hence it is non-reactive.

If two compounds have the same empirical formula but different molecular fomulae they must have
  • a)
    different percentage composition 
  • b)
    different molecular weight
  • c)
    same viscosity
  • d)
    same vapour density
Correct answer is option 'B'. Can you explain this answer?

Gaurav Kumar answered
TIPS/Formulae : Empirical Formula = n × Molecular formula
Solution : Since the molecular formula is n times the empirical formula, therefore, different compounds having the same empirical formula must have different molecular weights.

In the compound given below the correct order of the acidity of the positions X, Y and Z is
  • a)
    Z > X > Y
  • b)
    X > Y > Z
  • c)
    X > Z > Y
  • d)
    Y > X > Z
Correct answer is option 'B'. Can you explain this answer?

Tarun Kaushik answered
(i) Position (X) is most acidic due to – COOH group.
(ii) –NH3+ group at position Y is more acidic than at Z because of presence of electron withdrawing – COOH group in close proximity. Hence – NH3+ group at position Z is least acidic.

The major product obtained when Br2/Fe is treated with
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'B'. Can you explain this answer?

Ananya Das answered
TIPS/Formulae :– NH is an activating group where as  group is a deactivating group.
Hence electrophilic substitution will be governed by the ring having 

An organic compound having molecular mass 60 is found to contain  C = 20%, H = 6.67% and N = 46.67% while rest is oxygen. On heating it gives NH3 alongwith a solid residue.
The solid residue give violet colour with alkaline copper sulphate solution. The compound is
  • a)
    CH3CH2CONH2
  • b)
    (NH2)2 CO
  • c)
    CH3CONH2
  • d)
    CH3NCO
Correct answer is option 'B'. Can you explain this answer?

Utkarsh Pandey answered
Given: C=20% , H=6.67% and N=46.67%  

Therefore O= 100-(20 + 6.67 + 46.67) = 26.66%

Mol mass is given at 60

Wt. of each element = C= 20% = 12 i.e 1 atom of C as at mass of C=12

 H = 6.67% = 4 i.e. 4 atoms of H

 N = 46.67% = 28 i.e. 2 atoms of N

 O = 26.66% = 15.96 = 1 atom of O

Mol formula =  CH4N2O =

As the copper sulphate changes color the test implies presence of peptide bond. -CO-NH-

Also, the loss of NH3 on heating also justifies this fact

Hence the structure should be NH2-CO-NH2

Considering the basic strength of amines in aqueous solution, which one has the smallest pKb value?   
  • a)
    (CH3)2NH
  • b)
    CH3NH2
  • c)
    (CH3)3N
  • d)
    C6H5NH2
Correct answer is option 'A'. Can you explain this answer?

Anaya Patel answered
Arylamines are less basic than alkyl amines and even ammonia. This is due to resonance. In aryl amines the lone pair of electrons on N is partly shared with the ring and is thus less available for sharing with a proton.
In alkylamines, the electron releasing alkyl group increases the electron density on nitrogen atom and thus also increases the ability of amine for protonation.
Hence more the no. of alkyl groups higher should be the basicity of amine. But a slight discrepancy occurs in case of trimethyl amines due to steric effect. Hence the correct  order is
(CH3)2 NH > CH3NH2> (CH3)3 N> C6H5 NH2

The correct order of increasing basic nature for the bases NH3, CH3NH2 and (CH3)2 NH is
  • a)
    (CH3)2NH < NH3 < CH3NH2
  • b)
    NH3 < CH3NH2 < (CH3)2NH
  • c)
    CH3NH2 < (CH3)2NH < NH3
  • d)
    CH3NH2 < NH3 < (CH3)2NH
Correct answer is option 'B'. Can you explain this answer?

Utkarsh Pandey answered
Except the amines containing tertiary butyl group, all lower aliphatic amines are stronger bases than ammonia because of +I (inductive) effect. The alkyl groups, which are electron releasing groups, increase the electron density around the nitrogen thereby, increasing the availability of the lone pair of electrons to proton or Lewis acids and making the amine more basic.

The observed order in the case of lower members is found to be as secondary > primary > tertiary. This anomalous behavior of tertiary amines is due to steric factors i.e. crowding of alkyl groups cover nitrogen atom from all sides and thus makes it unable for protonation. Thus the relative strength is in order (CH3)2NH > CH3NH2 > NH3.

Amongst the following the most basic compound is
  • a)
    p -nitroaniline
  • b)
    acetanilide
  • c)
    aniline
  • d)
    benzylamine
Correct answer is option 'D'. Can you explain this answer?

Benzylamine is a stronger base than aniline because

The lone pair of electrons on the nitrogen atom in benzylamine is delocalized.
The lone pair of electrons on the nitrogen atom in aniline is delocalized.
The lone pair of electrons on the nitrogen atom in aniline is not involved in resonance.
Benzylamine has a higher molecular mass than aniline.

Among the following, the strongest base is
  • a)
    C6H5NH2
  • b)
    p-NO2.C6H4NH2
  • c)
    m-NO2.C6H4.NH2
  • d)
    C6H5CH2NH2
Correct answer is option 'D'. Can you explain this answer?

Krishna Iyer answered
Aliphatic amines are more basic than aromatic amines because in aliphatic amines electron pair on nitrogen is not involved in resonance.

Amongst the following, the most basic compound is :
  • a)
    Benzylamine
  • b)
    Aniline
  • c)
    Acetanilide
  • d)
    p-Nitroaniline
Correct answer is option 'A'. Can you explain this answer?

Muskaan Roy answered
Most basic compound amongst the given options: Benzylamine (option A)

Explanation:

Introduction:
In organic chemistry, basicity refers to the ability of a compound or molecule to accept a proton (H+) or donate a pair of electrons. The basicity of a compound depends on the availability of lone pairs of electrons on the atom or group of atoms.

Benzylamine (option A):
- Benzylamine is an organic compound with the formula C6H5CH2NH2.
- It consists of a benzene ring (C6H5) attached to an amino group (-NH2) through a methylene group (CH2).
- The lone pair of electrons on the nitrogen atom in the amino group can act as a Lewis base and readily accept a proton (H+).
- The lone pair of electrons is available for donation due to the electron-withdrawing nature of the benzene ring, which increases the basicity.

Aniline (option B):
- Aniline is an organic compound with the formula C6H5NH2.
- It consists of a benzene ring (C6H5) attached to an amino group (-NH2).
- The lone pair of electrons on the nitrogen atom in the amino group can also act as a Lewis base and accept a proton (H+).
- However, compared to benzylamine, aniline is less basic due to the electron-donating nature of the benzene ring. The lone pair of electrons is less available for donation.

Acetanilide (option C):
- Acetanilide is an organic compound with the formula C6H5NH(C2H3O).
- It consists of a benzene ring (C6H5) attached to an acetyl group (-C2H3O) through an amino group (-NH).
- The lone pair of electrons on the nitrogen atom in the amino group can also act as a Lewis base and accept a proton (H+).
- However, the presence of the acetyl group decreases the basicity compared to aniline. The electron-withdrawing nature of the acetyl group decreases the availability of the lone pair of electrons.

p-Nitroaniline (option D):
- p-Nitroaniline is an organic compound with the formula C6H6N2O2.
- It consists of a benzene ring (C6H6) attached to an amino group (-NH2) and a nitro group (-NO2) at the para position (opposite to the amino group).
- The lone pair of electrons on the nitrogen atom in the amino group can also act as a Lewis base and accept a proton (H+).
- However, the presence of the nitro group decreases the basicity compared to aniline. The electron-withdrawing nature of the nitro group decreases the availability of the lone pair of electrons.

Conclusion:
Amongst the given options, benzylamine (option A) is the most basic compound. The electron-withdrawing nature of the benzene ring increases the availability of the lone pair of electrons on the nitrogen atom, making benzylamine more basic compared to aniline, acetanilide, and p-nitroaniline.

Hydrogen bonding plays a central role in the following phenomena
  • a)
    Ice floats in water
  • b)
    Higher Lewis basicity of primary amines than tertiary amines in aqueous solutions
  • c)
    Formic acid is more acidic than acetic acid
  • d)
    Dimerisation of acetic acid in benzene
Correct answer is option 'A,B,D'. Can you explain this answer?

Jyoti Saha answered
In ice, water molecules are excessively H-bonded giving a cage-like structure which is lighter than water.
Primary amines are more basic than tertiary amine, because the protonated 1° amines are extensively H-bonded and hence more stable than the corresponding protonated 3° amines.
Acetic acid undergoes dimerisation in benzene.

In the reaction
the product E is :
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'A'. Can you explain this answer?

Yash Modi answered
In D, the NH2 Will be replaced by N2Cl, and in E the N2Cl will be replaced by CN.( Sandmeyer Reaction). So ans is A

Which one of the following is the strongest base in aqueous solution ?
  • a)
    Methylamine
  • b)
    Trimethylamine
  • c)
    Aniline
  • d)
    Dimethylamine.
Correct answer is option 'D'. Can you explain this answer?

Baby Ghosh answered
Due to steric hindrance,solvanation of ions and the combined effect of the pushing effect of alkyl grp(+I) ,strric hindrance and the salvation of amines cause the basicity order should be ....NH3

The most unlikely representation of resonance structures of p-nitrophenoxide ion is
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'C'. Can you explain this answer?

Hansa Sharma answered
N can't have more than 8 electrons in its valence shell as it does not have any d orbital. In (c), N has 10 electrons.

In the reaction shown below, the major product(s) formed is/ are
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'A'. Can you explain this answer?

Manisha Kumar answered
group is acetylated by acetic anhydride in methylene chloride (solvent). Note that —CONH2 group does not undergo acetylation because here lone pair of electrons is delocalised.

The correct order of basicities of the following compounds is
2. CH3 - CH2 - NH2
3. (CH3)2NH
  • a)
    2 > 1 > 3 > 4
  • b)
    1 > 3 > 2 > 4
  • c)
    3 > 1 > 2 > 4
  • d)
    1 > 2 > 3 > 4
Correct answer is option 'B'. Can you explain this answer?

Anand Kumar answered
4 has lowest basic character because lone pair present at N is involve in delocalization through +R of O.
In 2 NH2 is 1degree while in 3 N is 3degree and we know 3degree has high basic character than 1degree.
Finally 1, it has two spots to donate e and has highest tendency to donate e.
So, option B is correct.

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