Chapter 9: Amines Assertion-Reason Questions | chemistry Class 12 CBSE

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 1

Logic Check

Assertion (A): Nitrogen in amines is sp3 hybridised and amines have a pyramidal geometry. Reason (R): Nitrogen in amines has three bonding pairs and one lone pair of electrons, following VSEPR theory.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 2

Logic Check

Assertion (A): Primary amines have higher boiling points than tertiary amines of similar molar mass. Reason (R): Primary amines have two N–H bonds available for intermolecular hydrogen bonding, while tertiary amines have none.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 3

Logic Check

Assertion (A): Aniline is a weaker base than methylamine. Reason (R): In aniline, the lone pair on nitrogen is delocalised into the benzene ring by resonance, making it less available for protonation.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 4

Logic Check

Assertion (A): Aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis. Reason (R): Aryl halides do not undergo nucleophilic substitution with the phthalimide anion.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 5

Logic Check

Assertion (A): Arenediazonium salts are more stable than alkyldiazonium salts. Reason (R): In arenediazonium salts, the positive charge is stabilised by delocalisation into the benzene ring through resonance.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 6

Logic Check

Assertion (A): Aliphatic amines are stronger bases than ammonia. Reason (R): Alkyl groups have a negative inductive effect (−I effect) that withdraws electron density from nitrogen.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 7

Logic Check

Assertion (A): Aniline undergoes tribromination easily when treated with bromine water even at room temperature. Reason (R): The –NH2 group is a powerful ortho- and para-activating group that greatly increases the electron density of the benzene ring.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 8

Logic Check

Assertion (A): Carbylamine reaction is used as a test for secondary amines. Reason (R): Secondary amines on heating with CHCl3 and alc. KOH give foul-smelling isocyanides.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 9

Logic Check

Assertion (A): In the Hoffmann bromamide degradation, the amine formed has one carbon atom less than the amide. Reason (R): An alkyl/aryl group migrates from the carbonyl carbon to the nitrogen atom, and the carbonyl carbon is lost as carbonate.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 10

Logic Check

Assertion (A): Aniline does not undergo Friedel-Crafts alkylation. Reason (R): Aniline reacts with the Lewis acid catalyst AlCl3 to form a salt, after which nitrogen acquires positive charge and acts as a strong ring deactivator.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 11

Logic Check

Assertion (A): Lower aliphatic amines are soluble in water but higher amines are not. Reason (R): Higher amines have a larger hydrophobic alkyl part that prevents hydrogen bonding with water.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 12

Logic Check

Assertion (A): The Sandmeyer reaction gives better yields than the Gattermann reaction for the synthesis of aryl chlorides or bromides. Reason (R): Sandmeyer reaction uses Cu(I) ions as catalysts, which are more effective than copper powder used in Gattermann reaction.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 13

Logic Check

Assertion (A): Amines behave as Lewis bases. Reason (R): Amines have an unshared (lone) pair of electrons on the nitrogen atom which can be donated to a Lewis acid.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 14

Logic Check

Assertion (A): Ammonolysis of alkyl halides with excess ammonia gives primary amine as the major product. Reason (R): Excess ammonia suppresses the formation of secondary and tertiary amines by statistically favouring the initial substitution.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 15

Logic Check

Assertion (A): Aniline salts (anilinium salts) are soluble in water but insoluble in organic solvents. Reason (R): Aniline salts are ionic compounds that interact with polar water through ion-dipole interactions.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 16

Logic Check

Assertion (A): Direct nitration of aniline gives substantial amount of m-nitroaniline. Reason (R): In strongly acidic conditions, –NH2 of aniline is protonated to –NH3+, which is a meta-directing group.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 17

Logic Check

Assertion (A): Reduction of nitriles with LiAlH4 is useful for ascending the amine series. Reason (R): Reduction of RCN gives RCH2NH2, where the product amine has the same number of carbon atoms as the nitrile.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 18

Logic Check

Assertion (A): Benzenediazonium chloride decomposes on warming in water to give phenol. Reason (R): At around 283 K, the diazonium salt undergoes hydrolysis where water acts as a nucleophile replacing the diazonium group.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 19

Logic Check

Assertion (A): N-ethylbenzenesulphonamide (product of primary amine with Hinsberg's reagent) is soluble in alkali. Reason (R): The N–H bond in the sulphonamide is strongly acidic due to the electron-withdrawing sulphonyl group.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 20

Logic Check

Assertion (A): Ethylamine is soluble in water whereas aniline is not. Reason (R): Ethylamine can form hydrogen bonds with water, while aniline, despite having an –NH2 group, is less polar due to the larger hydrophobic benzene ring.

Reasoning Options

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Chapter sections

Chapter 9: Amines | Assertion-Reason

Assertion (A): Nitrogen in amines is sp3 hybridised and amines have a pyramidal geometry. Reason (R): Nitrogen in amines has three bonding pairs and one lone pair of electrons, following VSEPR theory.

Assertion (A): Primary amines have higher boiling points than tertiary amines of similar molar mass. Reason (R): Primary amines have two N–H bonds available for intermolecular hydrogen bonding, while tertiary amines have none.

Assertion (A): Aniline is a weaker base than methylamine. Reason (R): In aniline, the lone pair on nitrogen is delocalised into the benzene ring by resonance, making it less available for protonation.

Assertion (A): Aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis. Reason (R): Aryl halides do not undergo nucleophilic substitution with the phthalimide anion.

Assertion (A): Arenediazonium salts are more stable than alkyldiazonium salts. Reason (R): In arenediazonium salts, the positive charge is stabilised by delocalisation into the benzene ring through resonance.

Assertion (A): Aliphatic amines are stronger bases than ammonia. Reason (R): Alkyl groups have a negative inductive effect (−I effect) that withdraws electron density from nitrogen.

Assertion (A): Aniline undergoes tribromination easily when treated with bromine water even at room temperature. Reason (R): The –NH2 group is a powerful ortho- and para-activating group that greatly increases the electron density of the benzene ring.

Assertion (A): Carbylamine reaction is used as a test for secondary amines. Reason (R): Secondary amines on heating with CHCl3 and alc. KOH give foul-smelling isocyanides.

Assertion (A): In the Hoffmann bromamide degradation, the amine formed has one carbon atom less than the amide. Reason (R): An alkyl/aryl group migrates from the carbonyl carbon to the nitrogen atom, and the carbonyl carbon is lost as carbonate.

Assertion (A): Aniline does not undergo Friedel-Crafts alkylation. Reason (R): Aniline reacts with the Lewis acid catalyst AlCl3 to form a salt, after which nitrogen acquires positive charge and acts as a strong ring deactivator.

Assertion (A): Lower aliphatic amines are soluble in water but higher amines are not. Reason (R): Higher amines have a larger hydrophobic alkyl part that prevents hydrogen bonding with water.

Assertion (A): The Sandmeyer reaction gives better yields than the Gattermann reaction for the synthesis of aryl chlorides or bromides. Reason (R): Sandmeyer reaction uses Cu(I) ions as catalysts, which are more effective than copper powder used in Gattermann reaction.

Assertion (A): Amines behave as Lewis bases. Reason (R): Amines have an unshared (lone) pair of electrons on the nitrogen atom which can be donated to a Lewis acid.

Assertion (A): Ammonolysis of alkyl halides with excess ammonia gives primary amine as the major product. Reason (R): Excess ammonia suppresses the formation of secondary and tertiary amines by statistically favouring the initial substitution.

Assertion (A): Aniline salts (anilinium salts) are soluble in water but insoluble in organic solvents. Reason (R): Aniline salts are ionic compounds that interact with polar water through ion-dipole interactions.

Assertion (A): Direct nitration of aniline gives substantial amount of m-nitroaniline. Reason (R): In strongly acidic conditions, –NH2 of aniline is protonated to –NH3+, which is a meta-directing group.

Assertion (A): Reduction of nitriles with LiAlH4 is useful for ascending the amine series. Reason (R): Reduction of RCN gives RCH2NH2, where the product amine has the same number of carbon atoms as the nitrile.

Assertion (A): Benzenediazonium chloride decomposes on warming in water to give phenol. Reason (R): At around 283 K, the diazonium salt undergoes hydrolysis where water acts as a nucleophile replacing the diazonium group.

Assertion (A): N-ethylbenzenesulphonamide (product of primary amine with Hinsberg's reagent) is soluble in alkali. Reason (R): The N–H bond in the sulphonamide is strongly acidic due to the electron-withdrawing sulphonyl group.

Assertion (A): Ethylamine is soluble in water whereas aniline is not. Reason (R): Ethylamine can form hydrogen bonds with water, while aniline, despite having an –NH2 group, is less polar due to the larger hydrophobic benzene ring.

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