Organic Compounds Containing Nitrogen Questions — NEET Chemistry

Q1

\begin{aligned} &\text{ The following two reactions give the same foul smelling product } Z \text{. }\\ &\mathrm{C}_2 \mathrm{H}_5 \mathrm{Cl} \xrightarrow{\mathrm{X}} \mathrm{Z} \end{aligned}

X

and

Z

, respectively, are :

A

\mathrm{X}=\mathrm{AgCN} ; \mathrm{Z}=\mathrm{C}_2 \mathrm{H}_5 \mathrm{NC}

B

\mathrm{X}=\mathrm{KCN} ; \mathrm{Z}=\mathrm{C}_2 \mathrm{H}_5 \mathrm{CN}

C

\mathrm{X}=\mathrm{AgCN} ; \mathrm{Z}=\mathrm{C}_2 \mathrm{H}_5 \mathrm{CN}

D

\mathrm{X}=\mathrm{KCN} ; \mathrm{Z}=\mathrm{C}_2 \mathrm{H}_5 \mathrm{NC}

Correct Answer

Option A

Solution

\mathrm{C}_2 \mathrm{H}_5 \mathrm{Cl} \xrightarrow{\mathrm{AgCN}} \underset{\text{ (foul smell compound) }}{\mathrm{C}_2 \mathrm{H}_5 \mathrm{NC}(\mathrm{Z})}

\begin{aligned} & \text{ So, } X=\mathrm{AgCN} \\ & Z=\mathrm{C}_2 \mathrm{H}_5 \mathrm{NC} \end{aligned}

Q2

\text{ Two products } X \text{ and } Y \text{ are formed in the following reaction sequence. }

The suitable method that can be used for the separation of products X and Y is :

A Fractional distillation

B Sublimation

C Differential extraction

D Continuous extraction

Correct Answer

Option A

Solution

The ortho and para isomers are separated by fractional distillation under reduced pressure. o-isomer, (M.P.

$\rightarrow-4^{\circ} \mathrm{C}$ , B.P. $\rightarrow 222^{\circ} \mathrm{C}$ ) p-isomer, (M.P.

$\rightarrow 54^{\circ} \mathrm{C}$ , B.P.

$\rightarrow 238^{\circ} \mathrm{C}$ )

Q3

The correct order of decreasing basic strength of the given amines is: Answer (1) Sol. Lower is the value of

\mathrm{pK}_{\mathrm{b}}

, higher is the basicity Also aliphatic amines are stronger bases than aromatic amines.

\mathrm{pK}_{\mathrm{b}}

: Benzenamine > N-Methylaniline > Ethanamine > N-Ethylethanamine Basic strength : N-Ethylethanamine > Ethanamine > N-Methylaniline > Benzenamine

A N -ethylethanamine > ethanamine > N-methylaniline > benzenamine

B benzenamine

>

ethanamine

>\mathrm{N}

-methylaniline

>\mathrm{N}

-ethylethanamine

C N -methylaniline > benzenamine > ethanamine > N-ethylethanamine

D N-ethylethanamine > ethanamine > benzenamine > N-methylaniline

Correct Answer

Option A

Solution

Lower is the value of $\mathrm{pK}_{\mathrm{b}}$ , higher is the basicity Also aliphatic amines are stronger bases than aromatic amines. pKb : Benzenamine > N-Methylaniline > Ethanamine > N-Ethylethanamine Basic strength : N-Ethylethanamine > Ethanamine > N-Methylaniline > Benzenamine

Q4

The compound that does not undergo Friedel-Crafts alkylation reaction but gives a positive carbylamine test is :

A Aniline

B Pyridine

C N-methylaniline

D Triethylamine

Correct Answer

Option A

Solution

For positive carbylamine test, there must be the presence of primary amine.

Q5

Which of the following sequence of reactions is suitable to synthesize chlorobenzene?

A Benzene, Cl 2 , anhydrous FeCl 3

B Phenol, NaNO 2 , HCl, CuCl

C

D

Correct Answer

Option A

Solution

Benzene reacts with chlorine in presence of anhydrous FeCl 3 to give chlorobenzene.

Q6

The correct order of the basic strength of methyl substituted amines in aqueous solution is :

A (CH 3 ) 3 N > (CH 3 ) 2 NH > CH 3 NH 2

B CH 3 NH 2 > (CH 3 ) 2 NH > (CH 3 ) 3 N

C (CH 3 ) 2 NH > CH 3 NH 2 > (CH 3 ) 3 N

D (CH 3 ) 3 N > CH 3 NH 2 > (CH 3 ) 2 NH

Correct Answer

Option C

Solution

The basic strength of methyl substituted amines in aqueous form is together affected by inductive effect, solvation effect and steric hindrance.

So, the correct order of basic strength will be : (CH 3 ) 2 NH > CH 3 NH 2 > (CH 3 ) 3 N

Q7

Nitration of aniline in strong acidic medium also gives m-nitroaniline because

A inspite of substituents nitro group always goes to only m-position

B in electrophilic substitution reactions amino group is meta directive

C in absence of substituents nitro group always goes to m-position

D in acidic (strong) medium aniline is present as anilinium ion.

Correct Answer

Option D

Solution

In acidic medium, aniline is protonated to form anilinium ion which is m-directing.

Hence besides para (51%) and ortho (2%), meta product (47%) is also formed in significant yield.

Q8

The correct increasing order of basic strength for the following compounds is

A III < I < II

B III < II < I

C II < I < III

D II < III < I

Correct Answer

Option C

Solution

– NO 2 group has strong – R effect and – CH 3 shows +R effect. $\therefore$ Order of basic strength is

Q9

Which of the following reactions is appropriate for converting acetamide to methanamine?

A Hoffmann hypobromamide reaction

B Stephen's reaction

C Gabriel phthalimide synthesis

D Carbylamine reaction

Correct Answer

Option A

Solution

It is called Hoffmann's hypobromamide reaction.

Q10

The correct statement regarding the basicity of arylamines is

A arylamines are generally more basic than alkalmines because of aryl group

B arylamines are generally more basic than alkylmines, because the nitrogen atom in arylamines is sp -hybridised

C arylamines are generally less basic than alkylamines because the nitrogen lone-pair electrons are delocalised by interaction with the aromatic ring

\pi

-electron system

D arylamines are generally more basic than alkylamines because the nitrogen lone-pair electrons are not delocalised by interaction with the aromatic ring

\pi

-electron system.

Correct Answer

Option C

Solution

In arylamines, lone pair of electrons on nitrogen atom is delocalized over the benzene ring, thus not available for donation so arylamine are less basic than alkylamines.