NCERT Solutions for Class 12 Science Chemistry Chapter 13

Question 1:

Which of the following is a 3° amine?

(i) l-methylcyclohexylamine
(ii) Triethylamine
(iii) tert-butylamine
(iv) n-methylaniline

Answer:

The structure of the given amines are as follows
(a)

(b)

(c)

(d)

Since, the nitrogen in Triethylamine is directly linked to three carbon atoms, thus it forms a tertiary amine.

Hence, the correct answer is option (ii).

Question 2:

The correct IUPAC name for CH₂=CHCH₂NHCH₃ is

(i) Allylmethylamine
(ii) 2-amino-4-pentene
(iii) 4-aminopent-1-ene
(iv) N-methylprop-2-en-1-amine

Answer:

The correct IUPAC name of the given compound is N-methylprop-2-en-1-amine.

Hence, the correct answer is option (iv).

Question 3:

Amongst the following, the strongest base in aqueous medium is ____________.
(i) CH₃NH₂
(ii) NCCH₂NH₂
(iii) (CH₃)₂ NH
(iv) C₆H₅NHCH₃

Answer:

Alkyl groups show high electron releasing nature due to +I effect, due to which the lone pair of electrons of nitrogen are readily available for donation. Hence, secondary amines are more basic than primary amines.
Also, aliphatic amines are more basic than aromatic amines due to delocalization of lone pair of electrons of nitrogen atom into the benzene ring.
Therefore, (CH₃)₂NH is the strongest base.

Hence, the correct answer is option (iii).

Question 4:

Which of the following is the weakest Brönsted base?
(i)

(ii)

(iii)

(iv)

Answer:

The –NH₂ group in aniline is directly attached to the benzene ring, which leads to delocalization of lone pair of electrons of the nitrogen atom over the benzene ring. Thus making it less available for protonation.

Hence, the correct answer is option (i).

Question 5:

Benzylamine may be alkylated as shown in the following equation :

C₆H₅CH₂NH₂+ R—X → C₆H₅CH₂NHR

Which of the following alkylhalides is best suited for this reaction through S_N1 mechanism?

(i) CH₃Br
(ii) C₆H₅Br
(iii) C₆H₅CH₂Br
(iv) C₂H₅ Br

Answer:

S_N1 reaction occures throught the formation of carbocation. The greater stability of carbocation higher in the rate of reaction. Thus benzyl halide would be more reactive towards S_N1 reaction due to stabilization by resonance.

Hence, the correct answer is option (iii).

Question 6:

Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine?

(i) H₂ (excess)/Pt
(ii) LiAlH₄ in ether
(iii) Fe and HCl
(iv) Sn and HCl

Answer:

Aryl nitro compounds gives azo compounds on reduction with LiAlH₄ in dry ether. The reaction of nitrobenzene with LiAlH₄ in dry ether is as follows:

Hence, the correct answer is option (ii).

Question 7:

In order to prepare a 1° amine from an alkyl halide with simultaneous addition of one CH₂ group in the carbon chain, the reagent used as source of nitrogen is ___________.

(i) Sodium amide, NaNH₂
(ii) Sodium azide, NaN₃
(iii) Potassium cyanide, KCN
(iv) Potassium phthalimide, C₆H₄(CO)₂N^–K⁺

Answer:

Potassium cyanide (KCN) is used as a step-up reagent to increase the carbon atoms in the chain.

Hence, the correct answer is option (iii).

Question 8:

The source of nitrogen in Gabriel synthesis of amines is _____________.

(i) Sodium azide, NaN₃
(ii) Sodium nitrite, NaNO₂
(iii) Potassium cyanide, KCN
(iv) Potassium phthalimide, C₆H₄(CO)₂N^–K⁺

Answer:

The reaction of gabriel phthalimide synthesis is as follows: -

Thus, potassium phthalimide acts as a source of nitrogen in the synthesis.

Hence, the correct answer is option (iv).

Question 9:

Amongst the given set of reactants, the most appropriate for preparing 2° amine is _____.

(i) 2° R—Br + NH₃
(ii) 2° R—Br + NaCN followed by H₂/Pt
(iii) 1° R—NH₂+ RCHO followed by H₂/Pt
(iv) 1° R—Br (2 mol) + potassium phthalimide followed by H₃O⁺/heat

Answer:

Hence, the correct answer is option (iii).

Question 10:

The best reagent for converting 2–phenylpropanamide into 2-phenylpropanamine is _____.

(i) excess H₂
(ii) Br₂ in aqueous NaOH
(iii) iodine in the presence of red phosphorus
(iv) LiAlH₄ in ether

Answer:

The reaction is as follows:

Hence, the correct answer is option (iv).

Question 11:

The best reagent for converting, 2-phenylpropanamide into 1- phenylethanamine is ____.

(i) excess H₂/Pt
(ii) NaOH/Br₂
(iii) NaBH₄/methanol
(iv) LiAlH₄/ether

Answer:

The reaction is as follows:

Hence, the correct answer is option (ii).

Question 12:

Hoffmann Bromamide Degradation reaction is shown by __________.

(i) ArNH₂
(ii) ArCONH₂
(iii) ArNO₂
(iv) ArCH₂NH₂

Answer:

In Hoffmann Bromamide Degradation reaction, an amide is converted into a primary amine, throught intermolecular migration of phenyl group.

Hence, the correct answer is option (ii).

Question 13:

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

(i)

(ii)

(iii)

(i) II < III < I
(ii) III < I < II
(iii) III < II < I
(iv) II < I < III

Answer:

The basicity of a compound depends upon the presence of the group attached to the ring.
An electron withdrawing group contributes in decreasing the basic strength where as an electron donatiog group contributes in increaseing the basic strength. Therefore the correct order of increasing basic strength is as follows:

Hence, the correct answer is option (iv).

Question 14:

Methylamine reacts with HNO₂to form _________.

(i) CH₃—O—N=O
(ii) CH₃—O—CH₃
(iii) CH₃OH
(iv) CH₃CHO

Answer:

The reaction between methylamine with HNO₂ is as follows:

Hence, the correct answer is option (iii).

Question 15:

The gas evolved when methylamine reacts with nitrous acid is __________.

(i) NH₃
(ii) N₂
(iii) H₂
(iv) C₂H₆

Answer:

The reaction between methylamine and nitrous acid yields diazonium salts, which being unstable, liberate nitrogen gas quantitatively and alcohol. The reaction is as follows:

Hence, the correct answer is option (ii).

Question 16:

In the nitration of benzene using a mixture of conc. H₂SO₄ and conc. HNO₃ ,the species which initiates the reaction is __________.

(i) NO₂
(ii) NO⁺

$(iii) {NO}_{2}^{+} (iv) {NO}_{2}^{-}$

Answer:

The active species in the nitration of benzene nitronium ion $({NO}_{2}^{+})$ , which is generated by the mixture of conc. H₂SO₄ and conc. HNO₃.
${NO}_{2}^{+}$ acts as an electrophile in the reaction.

Hence, the correct answer is option (iii).

Question 17:

Reduction of aromatic nitro compounds using Fe and HCl gives __________.

(i) aromatic oxime
(ii) aromatic hydrocarbon
(iii) aromatic primary amine
(iv) aromatic amide

Answer:

The reduction of aromatic nitro compound using Fe and HCl give primary aromatic amines. The reaction is as follows:

Hence, the correct answer is option (iii).

Question 18:

The most reactive amine towards dilute hydrochloric acid is ___________.

(i)

(ii)

(iii)

(iv)

Answer:

The reactivity of an amine with dil HCl depends upon the strength of base. Greater the strength of the base, greater will be its reactivity towards dil HCl. Since, (CH₃)₂NH is highly basic of all the given compounds, thus it will show high reactivity.

Hence, the correct answer is option (ii).

Question 19:

Acid anhydrides on reaction with primary amines give ____________.

(i) amide
(ii) imide
(iii) secondary amine
(iv) imine

Answer:

The reaction of acid anhydride with primary produces amides. The reaction is as follows:

Hence, the correct answer is option (i).

Question 20:

$The reaction Ar {\overset{+}{N}}_{2} {Cl}^{-} \overset{Cu / HCl}{\to} ArCl + N_{2} + CuCl is named as$ _________.

(i) Sandmeyer reaction
(ii) Gatterman reaction
(iii) Claisen reaction
(iv) Carbylamine reaction

Answer:

The reaction of benzene diazonium salt with halogen acid in the presence of Cu to prepare corresponding aryl halides, is known as Gatterman reaction.
$Ar {\overset{+}{N}}_{2} {Cl}^{-} \overset{Cu / HCl}{\to} ArCl + N_{2} + CuCl$
Hence, the correct answer is option (ii).

Question 21:

Best method for preparing primary amines from alkyl halides without changing the number of carbon atoms in the chain is

(i) Hoffmann Bromamide reaction
(ii) Gabriel phthalimide synthesis
(iii) Sandmeyer reaction
(iv) Reaction with NH₃

Answer:

Gabriel phthalimide reaction is used for the preparation primary amines from alkyl halides without altering the number of carbon atoms in the chain.

Hence, the correct answer is option (ii).

Question 22:

Which of the following compound will not undergo azo coupling reaction with benzene diazonium chloride.

(i) Aniline
(ii) Phenol
(iii) Anisole
(iv) Nitrobenzene

Answer:

Diazonium cation being a weak electrophile does not react with compounds containing electro withdrawing group such as –NO₂ etc.
Hence, the correct answer is option (iv).

Question 23:

Which of the following compounds is the weakest Brönsted base?
(i)

(ii)

(iii)

(iv)

Answer:

Phenol being highly acidic amongst the given compounds, acts as the weakest Bronsted base.
Hence, the correct answer is option (iii).

Question 24:

Among the following amines, the strongest Brönsted base is __________.
(i)

(ii)
NH₃
(iii)

(iv)

Answer:

Pyrrolidine has the highest tendency to accept electron amongst the given compounds. This is because in pyrrolidine, lone pair of electrons in nitrogen is not involved in resonance and the presence of two alkyl groups also contributes in increasing the basic strength.
Hence, the correct answer is option (iv).

Question 25:

The correct decreasing order of basic strength of the following species is _______.
H₂O, NH_3, OH^–, ${NH}_{2}^{-}$

(i) ${NH}_{2}^{-}$ > OH^–> NH₃ > H₂O
(ii) OH^–> ${NH}_{2}^{-}$ > H₂O > NH₃
(iii) NH₃> H₂O > ${NH}_{2}^{-}$ > OH^–
(iv) H₂O > NH₃> OH^– > ${NH}_{2}^{-}$

Answer:

The basicity of the given compounds can be explained on the basis of the electronegativity and its tendency to accept protons.

Amide ion is most basic amongst the given compounds due to negative charge and two lone pair of electron.
Hence, the correct answer is option (i).

Question 26:

Which of the following should be most volatile?

(I)

(II)
(CH₃)₃N

(III)

(IV)

(i) II
(ii) IV
(iii) I
(iv) III

Answer:

Hydrocarbons lack hydrogen bonding whereas amines show considerable amount of hydrogen bonding. Thus are less volatile as compared to hydrocarbons. Therefore, hydrocarbons are highly volatile. Thus, CH₃CH₂CH₃ (IV) is most volatile among given options.

Hence, the correct answer is option (ii).

Question 27:

Which of the following methods of preparation of amines will give same number of carbon atoms in the chain of amines as in the reactant?

(i) Reaction of nitrite with LiAlH₄.
(ii) Reaction of amide with LiAlH₄ followed by treatment with water.
(iii) Heating alkylhalide with potassium salt of phthalimide followed by hydrolysis.
(iv) Treatment of amide with bromine in aqueous solution of sodium hydroxide.

Answer:

Treatment of amide with bromine in aqueous solution of sodium hydroxide yields amines with one carbon less than that present in amide. This is known as Hoffmmann's bromamide degradation reaction.
RCONH₂ + Br₂ + 4NaOH → R-NH₂ + Na₂CO₃ + 2NaBr + 2H₂O

Hence, the correct answer is option (iv).

Question 28:

In the following questions two or more options may be correct.

Which of the following cannot be prepared by Sandmeyer’s reaction?

(i) Chlorobenzene
(ii) Bromobenzene
(iii) Iodobenzene
(iv) Fluorobenzene

Answer:

Preparation of chloro and bromo arenes is favorable using Sandmeyer's reaction. The reactions are as follows:

Iodoarenes can be prepared by treating diazonium salt with potassium iodide.

For the preparation of fluoroarenes, arene diazonium chloride is treated with fluoroboric acid
ArN₂⁺Cl^- + HBF₄ → Ar-N₂⁺BF₄^- $\overset{∆}{\to}$ Ar-F + BF₃ + N₂

Hence, the correct answers are option (iii) and (iv).

Question 29:

In the following questions two or more options may be correct.

Reduction of nitrobenzene by which of the following reagent gives aniline?

(i) Sn/HCl
(ii) Fe/HCl
(iii) H₂-Pd
(iv) Sn/NH₄OH

Answer:

Reduction of nitro compounds to animes is done by passing hydrogen gas in the presence of niekel, palladium or platinum catalysts. Also, reduction can be carried out using metal in acidic medium. The reactions are as follows:

Hence, the correct answer are options (i),(ii) and (iii).

Question 30:

In the following questions two or more options may be correct.

Which of the following species are involved in the carbylamine test?
(i) R—NC
(ii) CHCl₃
(iii) COCl₂
(iv) NaNO₂+ HCl

Answer:

Aliphatic and aromatic primary amines on heating with chloroform and ethanolic potassium hydroxide forms isocyanide or carbylamines which are foul-smelling substance.
$R - {NH}_{2} + {CHCl}_{3} + 3 KOH \overset{Heat}{\to} R - NC + 3 KCl + 3 H_{2} O .$
Hence, the correct answer is option (i) and (ii).

Question 31:

In the following questions two or more options may be correct.

The reagents that can be used to convert benzenediazonium chloride to benzene are __________.

(i) SnCl₂/HCl
(ii) CH₃CH₂OH
(iii) H₃PO₂
(iv) LiAlH₄

Answer:

Diazonium salts can be converted to arenes using mild oxidising agents like hypophosphorous acid or ethanol.

$Ar {\overset{+}{N}}_{2} \bar{C} l + H_{3} {PO}_{2} + H_{2} O \overset{}{\to} ArH + N_{2} + H_{3} {PO}_{3} + HCl Ar {\overset{+}{N}}_{2} \bar{Cl} + {CH}_{3} {CH}_{2} OH \overset{}{\to} ArH + N_{2} + {CH}_{3} CHO + HCl$

Hence, the correct answer is option (ii) and (iii).

Question 32:

In the following questions two or more options may be correct.
The product of the following reaction is __________.

(i)

(ii)

(iii)

(iv)

Answer:

The reaction of N-acetylaniline with Br₂ in the presence acetic acid produces p-bromo-N-acetyl aniline (major) and o-bromo-N-acetyl aniline (minor) as products.

Hence, the correct answer are option (i) and (ii).

Question 33:

In the following questions two or more options may be correct.

Arenium ion involved in the bromination of aniline is __________.

(i)

(ii)

(iii)

(iv)

Answer:

Arenium ion formed in the process of bromination of aniline are as follows:

Hence, the correct answer is option (i), (ii) and (iii).

Question 34:

In the following questions two or more options may be correct.

Which of the following amines can be prepared by Gabriel synthesis.

(i) Isobutyl amine
(ii) 2-Phenylethylamine
(iii) N-methylbenzylamine
(iv) Aniline

Answer:

Gabriel synthesis can be used to prepare primary aliphatic amines. Thus, only isobutyl amine & 2-phenylethylamine can be prepared by this method.
Hence, the correct answer is option (i) and (ii).

Question 35:

In the following questions two or more options may be correct.

Which of the following reactions are correct?

Answer:

The correct reactions are

Hence, the correct answer is option (i) and (iii).

Question 36:

In the following questions two or more options may be correct.

Under which of the following reaction conditions, aniline gives p-nitro derivative as the major product?

(i) Acetyl chloride/pyridine followed by reaction with conc. H₂SO₄+conc. HNO₃.
(ii) Acetic anyhdride/pyridine followed by conc. H₂SO₄+ conc. HNO₃.
(iii) Dil. HCl followed by reaction with conc. H₂SO₄+ conc. HNO₃.
(iv) Reaction with conc. HNO₃+ conc.H₂SO₄.

Answer:

Aniline produces acctanilide on reaction with acetyl chloride or acetic anhydride in the presence of pyridine. N-acetyl aniline is ortho-para directing group, which produces majorly P-nitroaniline on nitroation. The reaction is as follows:

Hence, the correct answer is option (i) and (ii).

Question 37:

Which of the following reactions belong to electrophilic aromatic substitution?

(i) Bromination of acetanilide
(ii) Coupling reaction of aryldiazonium salts
(iii) Diazotisation of aniline
(iv) Acylation of aniline

Answer:

Bromination of acetanilide is an example of electrophilic substitution reaction

Also, the coupling reaction of aryldiazonium salt is also an example of electrophilic substitution reaction.

Hence, the correct answer is option (i) and (ii).

Question 38:

What is the role of HNO₃ in the nitrating mixture used for nitration of benzene?

Answer:

HNO₃ acts as a base in the reaction and helps in generating the electrophile, which is nitronium ion $({NO}_{2}^{+})$ in this reaction.

Question 39:

Why is NH₂group of aniline acetylated before carrying out nitration?

Answer:

On acetylation of aniline, the acetyl group being electron withdrawing attracts the lone pair of electron more towards the carbonyl group, as a result the activating effect of –NH₂is reduced i.e, the lone pair of electrons are less available for donation on the benzene ring. Thus, nitration can be carried out by protecting –NH₂by acetylation to give o – and p – nitroanilines.

On the other hand, direct nitration of aniline is not possible due to oxidation of –NH₂group.

Question 40:

What is the product when C₆H₅CH₂NH₂ reacts with HNO₂?

Answer:

The reaction is as follows:
$\begin{array}{l} C_{6} H_{5} {CH}_{2} {NH}_{2} + HONO \overset{HCl}{\to} C_{6} H_{5} {CH}_{2} {OH+N}_{2} ↑ + H_{2} O \\ Benzylamine Benzyl Alcohol \end{array}$

Question 41:

What is the best reagent to convert nitrile to primary amine?

Answer:

Nitrile can be converted into primary amines on reducing them with LiAIH₄ or sodium/alcohol

Question 42:

Give the structure of ‘A’ in the following reaction.

Answer:

The complete reaction is as follows:

Question 43:

What is Hinsberg reagent?

Answer:

Benzene sulphonyl chloride (C₆H₅SO₂Cl) is known as Hinsberg reagent. The structure is as follows:

It is used to distinguish between primary, secondary and tertiary amines.

Question 44:

Why is benzene diazonium chloride not stored and is used immediately after its preparation?

Answer:

Benzene diazonium chloride is stable at low temperature. But it is quite unstable at highest temperatures. Therefore, it cannot be stored and is used immediately after its preparation.

Question 45:

Why does acetylation of —NH₂ group of aniline reduce its activating effect?

Answer:

Acetylation of aniline, reduce the electron density of nitrogen due to lone pair of nitrogen and shifts it towards the carbonyl group. As a result of which the lone pair of electrons of nitrogen are less available for donation to benzene ring by resonance.

Therefore, activating effect of –NHCOCH₃group is less than –NH₂.

Question 46:

Explain why MeNH₂is stronger base than MeOH?

Answer:

As nitrogen is less electronegative than oxygen, therefore, lone pair of electrons on nitrogen is readily available for donation, which contributes to higher basicity of MeNH₂than MeOH.

Question 47:

What is the role of pyridine in the acylation reaction of amines?

Answer:

Pyridine contributes in eliminating the side products like, HCl formed during the reaction and shifts the equilibrium to the right hand side.

Question 48:

Under what reaction conditions (acidic/basic), the coupling reaction of aryldiazonium chloride with aniline is carried out?

Answer:

Coupling reaction of aryl diazonium chloride with aniline is in mild acidic conditions (pH = 4 – 5).

Question 49:

Predict the product of reaction of aniline with bromine in non-polar solvent such as CS₂.

Answer:

The presence of non-polar solvent (such as CS₂) reduces the activating effect of –NH₂group. Thus, it produces mono substituted products.

Question 50:

Arrange the following compounds in increasing order of dipole moment. CH₃CH₂CH₃, CH₃CH₂NH₂, CH₃CH₂OH

Answer:

Polar molecules have higher dipole moment than non-polar molecules. Thus, out of the given compounds propane will have least dipole moment. Also, oxygen being more electronegative than nitrogen, therefore dipole moment of ethyl alcohol is higher than that of ethyl aniline. Hence, the correct increasing order of dipole moment is as follows:
CH₃CH₂CH₃< CH₃CH₂NH₂< CH₃CH₂OH.

Question 51:

What is the structure and IUPAC name of the compound, allyl amine?

Answer:

The structure and name of a compound allylamine is as follows:
Structure: ${HC}_{2}^{3} = \overset{2}{CH} - \overset{1}{C} H_{2} {NH}_{2}$
IUPAC: Prop – 2 – en – 1 – amine

Question 52:

Write down the IUPAC name of

Answer:

The IUPAC name of the given compound is N, N-dimethylbenzenamine.

Question 53:

A compound Z with molecular formula C₃H₉N reacts with C₆H₅SO₂Cl to give a solid, insoluble in alkali. Identify Z.

Answer:

The compount 'Z' is an aliphatic amine. The reactant of 'Z' with C₆H₅SO₂Cl gives a solid which is insoluble in alkali, this implies the product does not have any replacable hydrogen attached to nitrogen. Therefore, the amine must be a secondary amine, i.e., ethymethylamine. The reaction is as follows:

Question 54:

A primary amine, RNH₂can be reacted with CH₃—X to get secondary amine, R—NHCH₃but the only disadvantage is that 3° amine and quaternary ammonium salts are also obtained as side products. Can you suggest a method where RNH₂ forms only 2° amine?

Answer:

Primary amines can be converted into 2º amine by carbylamine reaction followed by catalytic reduction of isocyanide obtained as a product of carbylamine reaction.

Question 55:

Complete the following reaction.

Answer:

The reaction exhibits azo-coupling of phenols. In mild alkaline conditions phenol moiety participates in the azo-coupling and para position of phenol is occupied.

Question 56:

Why is aniline soluble in aqueous HCl?

Answer:

Aniline on reaction with HCl for anilinium chloride salt which contributes to its solubility in aqueous HCl.

Question 57:

Suggest a route by which the following conversion can be accomplished.

Answer:

Question 58:

Identify A and B in the following reaction.

Answer:

Question 59:

How will you carry out the following conversions?

(i) toluene → p-toluidine
(ii) p-toluidine diazonium chloride → p-toluic acid

Answer:

(i)

(ii)

Question 60:

Write following conversions:

(i) nitrobenzene → acetanilide (ii) acetanilide → p-nitroaniline

Answer:

(i)

(ii)

Question 61:

A solution contains 1 g mol. each of p-toluene diazonium chloride and p- nitrophenyl diazonium chloride. To this 1 g mol. of alkaline solution of phenol is added. Predict the major product. Explain your answer.

Answer:

The reaction stated is an example of electrophilic aromatic substitution reaction. In alkaline medium, phenol gets converted to phenoxide ions (an electron rich species) which is more reactive towards electrophilic attack Aryldiazonium cation behaves as an electrophile in this reaction. Also, p-Nitrophenyldiazonium cation is stronger electrophile than p-toulene diazonium cation.
Hence, couples up potentially with phenol. The reaction can be depicted as:

Question 62:

How will you bring out the following conversion?

Answer:

Question 63:

How will you carry out the following conversion?

Answer:

Question 64:

How will you carry out the following conversion?

Answer:

Question 65:

How will you carry out the following conversions?

(i)

(ii)

Answer:

(i)

(ii)

Question 66:

Match the items of Column I and Column II in the given question.

Match the compounds given in Column I with the items given in Column II.

Column I	Column II
(i) Benzene sulphonyl chloride	(a) Zwitter ion
(ii) Sulphanilic acid	(b) Hinsberg reagent
(iii) Alkyl diazonium salts	(c) Dyes
(iv) Aryl diazonium salts	(d) Conversion to alcohols

Answer:

The correct items are as follows:

Compounds	Items
(i) Benzene sulphonyl chloride	(b) Hinsberg reagent
(ii) Sulphanilic acid	(a) Zwitter ion
(iii) Alkyl diazonium salts	(d) Conversion to alcohols
(iv) Aryl diazonium salts	(c) Dyes

Question 67:

Match the items of Column I and Column II in the given question.

Match the reactions given in Column I with the statements given in Column II.

Column I	Column II
(i) Ammonolysis	(a) Amine with lesser number of carbon atoms
(ii) Gabriel phthalimide synthesis	(b) Detection test for primary amines.
(iii) Hoffmann Bromamide reaction	(c) Reaction of phthalimide with KOH and R—X
(iv) Carbylamine reaction	(d) Reaction of alkylhalides with NH₃

Answer:

The correct statement are as follows:

Column I	Column II
(i) Ammonolysis	(d) Reaction of alkyl halides with NH₃
(ii) Gabriel phthalimide synthesis	(c) Reaction of phthalimide with KOH and R—X
(iii) Hoffmann Bromamide reaction	(a) Amine with a lesser number of carbon atoms
(iv) Carbylamine reaction	(b) Detection test for primary amines

Question 68:

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion: Acylation of amines gives a monosubstituted product whereas alkylation of amines gives polysubstituted product.
Reason: Acyl group sterically hinders the approach of further acyl groups.

(i) Both assertion and reason are wrong.
(ii) Both assertion and reason are correct statements but reason is not correct explanation of assertion.
(iii) Assertion is correct statement but reason is wrong statement.
(iv) Both assertion and reason are correct statements and reason is correct explanation of assertion.
(v) Assertion is wrong statement but reason is correct statement.

Answer:

Acetylation of amines gives a monosubstituted product because acetylation in amines is the replacement of hydrogen atom of –NH₂ or >N–H group by the acetyl group. The products obtained by acetylation reaction are known as amides. But alkylation gives polysubstituted product depending on type of amine - primary or secondary.

So, assertion is correct but reason is wrong.

Hence, the correct answer is option (iii).

Question 69:

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion: Hoffmann’s bromamide reaction is given by primary amines.
Reason: Primary amines are more basic than secondary amines.
(i) Both assertion and reason are true, and reason is the correct explanation of the assertion.

(ii) Both assertion and reason are true but reason is not the correct explanation of assertion.

(iii) Assertion is not true but reason is true.

(iv) Both assertion and reason are false.

Answer:

Hoffmamn's bromamide reaction is used for the preparation of amines from amides
$R - \overset{\overset{0}{| |}}{C} - {NH}_{2} + {Br}_{2} \overset{NaOH}{\to} R - {NH}_{2} + {Na}_{2} {CO}_{3} + 2 NaBr + 2 H_{2} O$
Alkyl group attached to n-atom of the amines show an electron-donating effect as a result to which secondary amines show more basicity than the primary amine.
So, both assertion and reason are wrong.
Hence, the correct answer is option (i).

Question 70:

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion :N-Ethylbenzene sulphonamide is soluble in alkali.
Reason :Hydrogen attached to nitrogen in sulphonamide is strongly acidic.

(i) Both assertion and reason are true, and reason is the correct explanation of the assertion.

(ii) Both assertion and reason are true but reason is not the correct explanation of assertion.

(iii) Assertion is not true but reason is true.

(iv) Both assertion and reason are false.

Answer:

N-ethylbenzene sulphonamide is soluble in an alkali because of the presence of acidic hydrogen in its structure.

The hydrogen attached to nitrogen in sulphonamide is strongly acidic.
So, both assertion and reason are correct and the reason is the correct explanation of assertion.
Hence, the correct answer is option (iv).

Question 71:

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion: N, N-Diethylbenzene sulphonamide is insoluble in alkali.
Reason: Sulphonyl group attached to nitrogen atom is strong electron-withdrawing group.

(i) Both assertion and reason are true, and reason is the correct explanation of the assertion.

(ii) Both assertion and reason are true but reason is not the correct explanation of assertion.

(iii) Assertion is not true but reason is true.

(iv) Both assertion and reason are false.

Answer:

The insolubility of N-diethylbenzene sulphonamide is due to the absence of acidic hydrogen in its structure. Also, the sulphonyl group attached to the nitrogen atom is electron-withdrawing group. So, both assertion and reason are correct but reason is not the correct explanation of assertion.
Hence, the correct answer is option (ii).

Question 72:

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion :Only a small amount of HCl is required in the reduction of nitro compounds with iron scrap and HCl in the presence of steam.
Reason: FeCl₂ formed gets hydrolysed to release HCl during the reaction.
(i) Both assertion and reason are true, and reason is the correct explanation of the assertion.

(ii) Both assertion and reason are true but reason is not the correct explanation of assertion.

(iii) Assertion is not true but reason is true.

(iv) Both assertion and reason are false.

Answer:

A small amount of HCl is required for the reduction nitro compound in the presence of iron scrap because FeCl₂ firned during the reaction gets hydrolysed to release HCl, that can maintain the reaction further.
So, both assertion and reason are correct and reason is the correct explanation of the assertion.
Hence, the correct answer is option (iv).

Question 73:

In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion: Aromatic 1° amines can be prepared by Gabriel Phthalimide Synthesis.
Reason: Aryl halides undergo nucleophilic substitution with anion formed by phthalimide.

(i) Both assertion and reason are true, and reason is the correct explanation of the assertion.

(ii) Both assertion and reason are true but reason is not the correct explanation of assertion.

(iii) Assertion is not true but reason is true.

(iv) Both assertion and reason are false.

Answer:

Gabriel phthalimide synthesis is used only for the preparation of primary amines. It does not leads to the synthesis of aromatic amines because aryl halides do not undergo nucleophilic substitution reaction with the anion formed by phthalimide.
So, both assertion and reason are incorrect.
Hence, the correct answer is option (i).

Question 74:

In the following question, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion : Acetanilide is less basic than aniline.
Reason: Acetylation of aniline results in the decrease of electron density on nitrogen.

(i) Both assertion and reason are true, and reason is the correct explanation of the assertion.

(ii) Both assertion and reason are true but reason is not the correct explanation of assertion.

(iii) Assertion is not true but reason is true.

(iv) Both assertion and reason are false.

Answer:

Acetanilide is less basic than aniline due decrease electron density on nitrogen due to the presence of acetly group.
So, both assertion and reason are correct and reason is the correct explanation of assertion.
Hence, the correct answer is option (iv).

Question 75:

A hydrocarbon ‘A’, (C₄H₈) on reaction with HCl gives a compound ‘B’, (C₄H₉Cl),which on reaction with 1 mol of NH₃ gives compound ‘C’, (C₄H₁₁N). On reacting with NaNO₂and HCl followed by treatment with water, compound ‘C’ yields an optically active alcohol, ‘D’. Ozonolysis of ‘A’ gives 2 mols of acetaldehyde. Identify compounds ‘A’ to ‘D’. Explain the reactions involved.

Answer:

(1) As the addition of HCl to hydrocarbon changes the molecular formula of the compound from C4H8 to C4Hqel, it shows that the compound A is an alkene.

(2) Compound B reacts with NH₃ to give amine

(3) Compound C yields diazonium salt with NaNO₂/HCl followed by hydrolysis that yields optically active alcohol.

(4) Since the alkene gives 2 moles of acetaldehyde on ozonolysis, therefore it is a symmetrical alkene.

Question 76:

A colourless substance ‘A’ (C₆H₇N) is sparingly soluble in water and gives a water soluble compound ‘B’ on treating with mineral acid. On reacting with CHCl₃and alcoholic potash ‘A’ produces an obnoxious smell due to the formation of compound ‘C’. Reaction of ‘A’ with benzene sulphonyl chloride gives compound ‘D’ which is soluble in alkali. With NaNO₂and HCl, ‘A’ forms compound ‘E’ which reacts with phenol in an alkaline medium to give an orange dye ‘F’. Identify compounds ‘A’ to ‘F’.

Answer:

Question 77:

Predict the reagent or the product in the following reaction sequence.

NCERT Solutions for Class 12 Science Chemistry Chapter 13 - Amines

Page No 180:

Question 1:

Answer:

Page No 180:

Question 2:

Answer:

Page No 180:

Question 3:

Answer:

Page No 180:

Question 4:

Answer:

Page No 181:

Question 5:

Answer:

Page No 181:

Question 6:

Answer:

Page No 181:

Question 7:

Answer:

Page No 181:

Question 8:

Answer:

Page No 181:

Question 9:

Answer:

Page No 182:

Question 10:

Answer:

Page No 182:

Question 11:

Answer:

Page No 182:

Question 12:

Answer:

Page No 182:

Question 13:

Answer:

Page No 182:

Question 14:

Answer:

Page No 183:

Question 15:

Answer:

Page No 183:

Question 16:

Answer:

Page No 183:

Question 17:

Answer:

Page No 183:

Question 18:

Answer:

Page No 183:

Question 19:

Answer:

Page No 184:

Question 20:

Answer:

Page No 184:

Question 21:

Answer:

Page No 184:

Question 22:

Answer:

Page No 184:

Question 23:

Answer:

Page No 185:

Question 24:

Answer:

Page No 185:

Question 25:

Answer:

Page No 185:

Question 26:

Answer:

Page No 185: