Test: MCQs (One or More Correct Option): Compounds Containing Nitrogen | JEE Advanced | 15 Questions MCQ Test Class 12 Chemistry 35 Years JEE Mains &Advance Past yr Paper JEE

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QUESTION: 1

The products of reaction of alcoholic silver nitrite with ethyl bromide are

A.
ethane
B.
ethene
C.
nitroethane
D.
ethyl alcohol
E.
ethyl nitrite

Solution:

TIPS/Formulae : Silver nitrite, being a salt of nitrous acid, occurs in two tautomeric forms.

ion from AgNO₂ may exist in two tautomeric forms, –O – N = O (nitrite ion) forming alkyl nitrites, and (nitro group) forming nitroalkanes.

2 C₂H₅Br + 2AgNO₂ → C₂H₅NO₂ + C₂H₅ONO + 2 AgBr

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QUESTION: 2

Reaction of with a mixture of Br₂ and KOH gives R-NH₂ as the main product. The intermediates involved in this reaction are :

A.
B.
R – NHBr
C.
R – N = C = O
D.

Solution:

This is an example of Hoffmann degradation of amides.

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QUESTION: 3

When nitrobenzene is treated with Br₂ in presence of FeBr ₃, the major product formed is m-bromonitrobenzene.
Statements which are related to obtain the m-isomer are

A.
The electron density on meta carbon is more than that on ortho and para positions
B.
The intermediate carbonium ion formed after initial attack of Br⁺ at the meta position is least destabilised
C.
Loss of aromaticity when Br⁺ attacks at the ortho and para positions and not at meta position
D.
Easier loss of H⁺ to regain aromaticity from the meta position than from ortho and para positions.

Solution:

TIPS/Formulae : Nitro group decreases the electron density at the meta-position in comparison to ortho and para position due to –I and –M effects.

The above intermediate is a resonance hybrid of three structures, hence is more stable than the corresponding intermediate from ortho and paraattack

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QUESTION: 4

Examine the following two structures for the anilinium ion and choose the correct statement from the ones given below:

A.
II is not an acceptable canonical structure because carbonium ions are less stable than ammonium ions.
B.
II is not an acceptable canonical structure because it is non-aromatic.
C.
II is not an acceptable canonical structure because the nitrogen has 10 valence electrons.
D.
II is an acceptable canonical structure

Solution:

In I^st structure N has complete octet , whereas in II^nd structure N has 10e in its valence shell.
Because of 1 double and 3 single bonds of N.

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QUESTION: 5

p-Chloroaniline and anilinium hydrochloride can be distinguished by

A.
Sandmeyer reaction
B.
NaHCO₃
C.
AgNO₃
D.
Carbylamine test

Solution:

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.

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QUESTION: 6

Among the following compounds, which will react with acetone to give a product containing > C = N–bond ?

A.
C₆H₅NH₂
B.
(CH₃)₃N
C.
C₆H₅NHC₆H5
D.
C₆H₅NHNH₂.

Solution:

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QUESTION: 7

Benzenediazonium chloride on reaction with phenol in weakly basic medium gives

A.
diphenyl ether
B.
p-hydroxyazobenzene
C.
chlorobenzene
D.
benzene

Solution:

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QUESTION: 8

A positive carbylamine test is given by

A.
N, N—dimethylaniline
B.
2, 4–dimethylaniline
C.
N–methyl-o-methylaniline
D.
p-methylbenzylamine

Solution:

NOTE : Only primary amines give carbylamine test.
Hence 2,4-dimethylanilinc and p-methyl–benzylamine both give this test.

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QUESTION: 9

In the reaction 2X + B₂H₆ → [BH₂(X)₂]⁺ [BH₄]^– the amine(s) X is (are)

A.
NH₃
B.
CH₃NH₂
C.
(CH₃)₂NH
D.
(CH₃)₃N

Solution:

Lower amines like NH₃, CH₃NH₂ and (CH₃)₂NH break diborane molecule unsymmetrically, while larger amines like (CH₃)₃N, C₅H₅N break diborane in symmetrical manner.

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QUESTION: 10

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

Solution:

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.

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QUESTION: 11

In the reaction shown below, the major product(s) formed is/ are

A.
B.
C.
D.

Solution:

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.