Here are 50 Assertion and Reason questions based on Chapter 13: “Organic Compounds Containing Nitrogen (Amines)” for CBSE Class 12 Chemistry.
Reason: The phenyl group in aniline withdraws electron density
from the nitrogen, making it less basic.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The phenyl group in aniline withdraws electron
density from the nitrogen via the conjugation effect, making the nitrogen less
available for protonation, thus reducing its basicity.
Reason: Nitrous acid reacts with the amino group of aniline to
form a diazonium ion by protonating the nitrogen.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Aniline reacts with nitrous acid (HNO2) to form a
diazonium salt through protonation of the amino group, which then undergoes the
formation of a diazonium ion.
Reason: Aliphatic amines have electron-donating alkyl groups,
making the nitrogen more available for protonation.
Answer: (E) Assertion is false, reason is false.
Explanation: Aromatic amines are less basic than aliphatic
amines because the phenyl group withdraws electron density from the nitrogen,
whereas alkyl groups in aliphatic amines donate electron density, enhancing
basicity.
Reason: The amino group in aniline activates the benzene ring
towards electrophilic substitution, facilitating bromination.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The amino group in aniline activates the aromatic
ring, making it more reactive towards electrophilic substitution, resulting in
the formation of 2,4,6-tribromoaniline (a white precipitate).
Reason: Methylamine forms hydrogen bonds with water more
effectively than aniline.
Answer: (D) Assertion is true, reason is false.
Explanation: Aniline has a phenyl group, which makes it less
soluble in water compared to methylamine, which has a smaller alkyl group that
interacts more effectively with water molecules through hydrogen bonding.
Reason: The amino group in aniline is less electron-donating
than in methylamine, making it less basic.
Answer: (C) Assertion is false, reason is true.
Explanation: Aniline has a lower pKa than methylamine due to
the electron-withdrawing effect of the phenyl group, making aniline less basic
and its conjugate acid less stable.
Reason: The lone pair of electrons on nitrogen in amines is
more available for protonation than the lone pair on oxygen in alcohols.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Nitrogen in amines has a more readily available
lone pair compared to oxygen in alcohols, making amines more basic.
Reason: Amines can form hydrogen bonds, leading to higher
boiling points than hydrocarbons.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines are capable of hydrogen bonding due to the
lone pair on nitrogen, which leads to higher boiling points compared to
hydrocarbons of similar molecular weight.
Reason: Amines act as nucleophiles and attack the electrophilic
carbonyl carbon in acyl chlorides.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The nucleophilic nitrogen in amines attacks the
electrophilic carbonyl carbon in acyl chlorides, leading to the formation of
amides.
Reason: Primary amines have two hydrogens attached to nitrogen,
which increases the availability of the lone pair for protonation.
Answer: (D) Assertion is true, reason is false.
Explanation: Primary amines are stronger bases than secondary
amines due to the higher electron-donating ability of two alkyl groups in
primary amines compared to only one in secondary amines.
Reason: The amino group of methylamine reacts with formaldehyde
to form a condensation product.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Methylamine reacts with formaldehyde to form a
Schiff's base through a condensation reaction, releasing water in the process.
Reason: Aniline undergoes nucleophilic substitution with acetyl
chloride, replacing the chlorine atom with an amide group.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Aniline reacts with acetyl chloride, where the
nitrogen of the amino group attacks the carbonyl carbon, resulting in the
formation of an amide.
Reason: The amino group in aromatic amines is
electron-donating, activating the benzene ring for electrophilic substitution.
Answer: (E) Assertion is false, reason is false.
Explanation: Aromatic amines are more reactive than alkyl
amines towards electrophilic substitution due to the electron-donating nature of
the amino group. However, the reason provided for alkyl amines is incorrect as
alkyl groups are also electron-donating.
Reason: Amines can form hydrogen bonds with water molecules due
to the lone pair on nitrogen.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The lone pair on nitrogen in amines allows them to
form hydrogen bonds with water molecules, leading to higher solubility in water
compared to hydrocarbons.
Reason: Alkyl groups are electron-donating, which increases the
electron density on nitrogen, enhancing its basicity.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The electron-donating effect of alkyl groups
increases the electron density on nitrogen, making the nitrogen more available
for protonation, thus increasing basicity.
Reason: Alkyl halides react with amines to form alkylated
amines by the substitution of halides.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines act as nucleophiles and react with alkyl
halides in nucleophilic substitution reactions to form higher amines.
Reason: Larger amines have less ability to form hydrogen bonds
with water molecules.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: As the molecular size of amines increases, the
solubility in water decreases due to the reduced ability of larger molecules to
form hydrogen bonds with water molecules.
Reason: Tertiary amines lack a hydrogen atom on nitrogen,
preventing the formation of a diazonium salt.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Tertiary amines lack a hydrogen on nitrogen,
preventing protonation and the formation of a diazonium ion upon reaction with
nitrous acid.
Reason: Primary amines have one alkyl group, secondary amines
have two alkyl groups, and tertiary amines have three alkyl groups attached to
nitrogen.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines are classified as primary, secondary, or
tertiary based on the number of alkyl groups attached to the nitrogen atom.
Reason: The nitrogen in primary amines has a hydrogen attached,
allowing protonation to form a diazonium ion.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Nitrous acid reacts with the amino group of
primary amines, leading to protonation and the formation of a diazonium salt.
Reason: The phenyl group in aniline withdraws electron density,
making the ring less reactive to electrophiles.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The phenyl group in aniline withdraws electron
density from the nitrogen, making the aromatic ring less reactive to
electrophilic substitution compared to methylamine, where the methyl group
donates electron density.
Reason: Aliphatic amines have more electron-donating groups,
which activate the aromatic ring more than in aromatic amines.
Answer: (C) Assertion is false, reason is true.
Explanation: Aromatic amines are more reactive towards
electrophilic substitution due to the activating effect of the amino group on
the benzene ring. Aliphatic amines, although electron-donating, are less
reactive due to less stabilization of the intermediate carbocation.
Reason: The nitrogen atom in amines has a lone pair of
electrons, which it can donate to form a bond with a proton.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The nitrogen atom in amines has a lone pair,
making amines basic as they can accept protons (H+).
Reason: Larger alkyl groups hinder the accessibility of the
nitrogen lone pair for protonation, making the amine less basic.
Answer: (D) Assertion is true, reason is false.
Explanation: The basicity of amines typically increases with
alkyl group size because larger alkyl groups push electron density towards the
nitrogen, making the lone pair more available for protonation. The statement is
false as it reverses the trend.
Reason: The amino group in aniline is protonated by nitrous
acid, leading to the formation of a diazonium ion.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Aniline reacts with nitrous acid (HNO2), where the
amino group is protonated and forms a diazonium salt.
Reason: The lone pair of electrons on nitrogen in amines
interacts with the electrophilic acyl group, preventing the formation of the
required catalyst.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines are not reactive towards Friedel-Crafts
acylation due to the nitrogen's lone pair, which can coordinate with the Lewis
acid catalyst, thus preventing the acylation reaction.
Reason: Methylamine reacts with nitrous acid to undergo
diazotization, releasing nitrogen gas and forming methyl alcohol.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Methylamine reacts with nitrous acid to form a
diazonium ion, which decomposes, releasing nitrogen gas and forming methyl
alcohol.
Reason: The nitrogen in amines has a lone pair of electrons
which is more basic and available for protonation compared to the lone pair on
oxygen in alcohols.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The nitrogen in amines is a better electron donor
compared to oxygen in alcohols because the nitrogen atom is less
electronegative, making its lone pair more available for donation.
Reason: The presence of electron-withdrawing groups in amines
reduces the electron density on nitrogen, making the lone pair less available
for protonation.
Answer: (C) Assertion is false, reason is true.
Explanation: Amines are typically stronger bases than ammonia
unless there are electron-withdrawing groups attached to the nitrogen. The
reasoning is true in specific cases but not generally for all amines.
Reason: The phenyl group in aryl amines withdraws electron
density from the nitrogen, reducing its availability for protonation.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The phenyl group in aryl amines withdraws electron
density from the nitrogen, reducing its basicity compared to alkyl amines, where
the alkyl groups donate electron density.
Reason: Tertiary amines have three alkyl groups, which donate
electron density to nitrogen, making its lone pair more available for
protonation.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The three electron-donating alkyl groups in
tertiary amines make the nitrogen's lone pair more available for protonation,
enhancing its basicity.
Reason: The amino group in aniline gets protonated in
hydrochloric acid, forming anilinium chloride, which is more soluble in water
than unprotonated aniline.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Aniline is more soluble in hydrochloric acid
because the amino group gets protonated to form anilinium chloride, which is
more water-soluble than the neutral aniline molecule.
Reason: The amino group is electron-donating through resonance,
making the aromatic ring more reactive towards electrophiles.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The amino group in aniline donates electron
density to the benzene ring via resonance, increasing the electron density and
activating the ring for electrophilic substitution.
Reason: Electron-withdrawing groups decrease the electron
density on nitrogen, making the lone pair less available for protonation.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Electron-withdrawing groups pull electron density
away from nitrogen, reducing its availability to accept protons, and thus
decreasing the basicity of amines.
Reason: The lone pair of electrons on nitrogen makes amines
nucleophilic.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines act as nucleophiles because the lone pair
of electrons on nitrogen can attack electrophilic centers in reactions.
Reason: Secondary amines have two alkyl groups that increase
the electron density on nitrogen, making it more nucleophilic than primary
amines.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Secondary amines are more nucleophilic than
primary amines due to the increased electron density provided by two alkyl
groups.
Reason: Electronegativity of substituents withdraws electron
density from the nitrogen, reducing its ability to accept a proton.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Electronegativity of substituents such as halogens
withdraws electron density from nitrogen, reducing its basicity by making the
nitrogen's lone pair less available for protonation.
Reason: The phenyl group in aromatic amines reduces their
ability to form hydrogen bonds with water molecules.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Aromatic amines are less soluble in water than
aliphatic amines due to the hydrophobic effect of the phenyl group, which
reduces hydrogen bonding with water.
Reason: The amino group in aryl amines is an activating group
that facilitates electrophilic substitution on the benzene ring.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The amino group in aniline is an electron-donating
group that activates the benzene ring, making it more reactive towards
electrophilic nitration.
Reason: The nitrogen lone pair attacks the electrophilic
carbonyl carbon in acyl chlorides, leading to the formation of an amide.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines react with acyl chlorides in a nucleophilic
acyl substitution reaction to form amides.
Reason: Tertiary amines have steric hindrance due to the bulky
alkyl groups, which make it harder for protonation to occur.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Tertiary amines, due to steric hindrance, are less
basic than primary amines because the lone pair of nitrogen is less available
for protonation.
Reason: Aniline is a weak base and reacts with acetic acid to
form a salt, aniline acetate.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Aniline is a weak base and reacts with acetic acid
to form aniline acetate, an amine salt.
Reason: Methylamine has an electron-donating methyl group that
increases the electron density on nitrogen, making it more basic than aniline.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: The methyl group in methylamine donates electron
density to nitrogen, making its lone pair more available for protonation
compared to aniline, where the phenyl group withdraws electron density from
nitrogen.
Reason: Larger alkyl groups reduce the ability of amines to
form hydrogen bonds with water molecules, decreasing solubility.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: As the size of the alkyl group increases, the
solubility of amines in water decreases because the alkyl groups reduce hydrogen
bonding with water.
Reason: Amines react with diazonium salts in the presence of an
alkaline medium to form azo compounds, which are highly colored.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Azo coupling reactions involve the reaction of
amines with diazonium salts, forming azo compounds that are used as dyes.
Reason: The lone pair of electrons on nitrogen in amines can
attack the electrophilic carbon in alkyl halides, leading to the substitution of
the halide ion.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines undergo nucleophilic substitution with
alkyl halides, where the lone pair on nitrogen displaces the halide ion, forming
an alkylated amine.
Reason: Primary aromatic amines react with nitrous acid to form
diazonium salts, which can be detected by their characteristic color.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Nitrous acid reacts with primary aromatic amines
to form diazonium salts, which are a diagnostic feature for identifying primary
aromatic amines.
Reason: The nitrogen atom in amines has a lone pair of
electrons that can accept a proton in acidic conditions, forming ammonium ions.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: In acidic conditions, the lone pair on nitrogen
accepts a proton, converting the amine into an ammonium ion.
Reason: Tertiary amines do not have a hydrogen attached to
nitrogen, preventing hydrogen bonding with water molecules.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Tertiary amines lack a hydrogen atom on nitrogen,
which is necessary for hydrogen bonding with water molecules.
Reason: Amines are electron-donating groups and activate the
aromatic ring, making it more reactive towards electrophiles.
Answer: (A) Assertion is true, reason is true, and reason is
the correct explanation for assertion.
Explanation: Amines, being electron-donating groups, activate
the aromatic ring and make it more reactive towards electrophilic substitution
reactions.