AminesNEET MCQs with solutions

Not quite — the answer is A.

In aqueous medium, secondary aliphatic amines are most basic due to +I effect and effective solvation of the conjugate acid. Primary aliphatic amines rank next. Aromatic amines are weaker because the nitrogen lone pair is delocalised into the benzene ring, reducing availability for protonation. N-methylaniline is more basic than benzenamine because one alkyl group partially offsets resonance loss. The correct order is therefore N-ethylethanamine > ethanamine > N-methylaniline > benzenamine.

Not quite — the answer is B.

Controlled dropwise addition of NaNO2 ensures steady in situ generation of HNO2 and prevents local excess, which would raise temperature and decompose the diazonium salt before collection. Slow addition is essential for yield, not just safety.

Not quite — the answer is B.

Secondary aliphatic amines are the strongest bases due to the +I effect of two alkyl groups and favourable solvation of the conjugate acid. Primary aliphatic amines are next. Aromatic amines are weakest because nitrogen lone pair delocalises into the ring, reducing availability for protonation.

Not quite — the answer is B.

In aqueous solution secondary aliphatic amines are most basic due to two +I groups and good solvation of conjugate acid. Primary aliphatic amines rank second. Aromatic amines are weakest because the lone pair delocalises into the ring. Thus: N-ethylethanamine > ethanamine > N-methylaniline > benzenamine.

Not quite — the answer is A.

Gabriel synthesis uses the alkyl halide directly via SN2 on potassium phthalimide, so the product amine has the same carbon count as the alkyl halide. Nitrile reduction adds one carbon; Hoffmann reaction removes one carbon — both alter chain length.

Not quite — the answer is A.

Primary aliphatic amines form highly unstable aliphatic diazonium salts that immediately decompose, yielding the corresponding alcohol with brisk N₂ evolution. Option B is the trap — stable diazonium salts form only with aromatic primary amines.

Not quite — the answer is A.

Dimethylamine balances maximum inductive effect with efficient solvation of its conjugate acid (dimethylammonium ion has two N-H bonds for H-bonding with water). Trimethylamine (C) has stronger inductive effect but its conjugate acid has only one N-H, severely limiting solvation. This solvation deficit drops (CH₃)₃N below (CH₃)₂NH in aqueous basicity.

Not quite — the answer is B.

Acetylation converts –NH₂ to –NHCOCH₃, a less activating amide group that allows controlled monosubstitution. Without protection, the highly activating –NH₂ causes rapid polysubstitution. Option D reverses the effect — acetylation slows, not speeds, EAS.

Not quite — the answer is A.

Primary amines possess two N-H bonds enabling strong intermolecular hydrogen bonding, significantly raising boiling point. Tertiary amines have no N-H bonds and cannot form intermolecular hydrogen bonds, hence lower boiling points. Van der Waals forces alone cannot compensate for absence of H-bonding.

Not quite — the answer is D.

Quaternary ammonium salts have four organic groups on nitrogen with a positive charge and no lone pair available — they are not amines. (CH₃)₄N⁺Cl⁻ fits this definition. All other options are amines with at least one lone pair on nitrogen.

Not quite — the answer is B.

Methanamine is the preferred IUPAC name for CH₃NH₂; the parent chain is methane with the suffix -amine. Methylamine is a retained common name, not strict IUPAC. Aminomethane and methylazane are non-standard forms.

Not quite — the answer is A.

NaNO2 and HCl generate HNO2 in situ which produces the electrophilic NO+. Low temperature (0–5°C) is mandatory because diazonium salts are thermally unstable and decompose above this range. Option B uses wrong reagents and wrong temperature.

Not quite — the answer is C.

Carbylamine test is specific to primary amines — only they possess the N-H bond needed to react with dichlorocarbene (:CCl₂) generated from CHCl₃/KOH. Secondary amines ((CH₃)₂NH) contain nitrogen but lack primary N-H, so no isocyanide forms. Aniline (A) is primary aromatic — it does give a positive test.

Not quite — the answer is C.

Resonance interaction between aniline's N lone pair and the benzene ring reduces electron density on nitrogen, making it far less available for protonation. Option B is the trap — aniline's nitrogen is actually sp² hybridized, not sp³.

Not quite — the answer is C.

Ethanamine follows IUPAC rules: parent chain ethane + suffix -amine. Ethylamine is the common name. Ethaneamine is a misspelling — the correct suffix drops the terminal 'e' of the alkane before adding -amine.

Not quite — the answer is C.

(CH₃)₂NH has two methyl groups on nitrogen; IUPAC names the longer (or either equal) chain as parent — methanamine — and the N-substituent as N-methyl, giving N-methylmethanamine. Dimethylamine is the common name only.

Not quite — the answer is B.

The longest chain on nitrogen is ethane (parent: ethanamine); the shorter methyl group is the N-substituent, giving N-methylethanamine. N-ethylmethanamine would mean the ethyl is on N and methane is the parent — reversed assignment.

Not quite — the answer is D.

N,N-dimethylethanamine has ethane as the parent chain and two methyl groups on nitrogen. CH₃CH₂N(CH₃)₂ fits this structure. (CH₃)₃N is trimethylamine — all three groups equal, parent is methanamine.

Not quite — the answer is A.

NH₂ is on C-1 of the three-carbon chain; strict IUPAC requires the locant, giving propan-1-amine. Propanamine without a locant is incomplete when positional ambiguity exists. Propylamine is the common name.

Not quite — the answer is B.

In IUPAC nomenclature, N- before a substituent name specifies that the group is bonded to nitrogen, not to a carbon of the parent chain. This distinguishes N-methylethanamine (methyl on N) from 2-methylpropanamine (methyl on C-2).

Not quite — the answer is A.

The NH₂ group is on C-2 of the propane chain; IUPAC suffix naming gives propan-2-amine. 2-Aminopropane uses NH₂ as a prefix, which applies only when NH₂ is not the principal group. Isopropylamine is the common name.

Not quite — the answer is B.

The strict IUPAC name of C₆H₅CH₂NH₂ is phenylmethanamine — methane is the parent chain with NH₂ (suffix) and phenyl on C-1. Benzylamine is an acceptable common name. Aniline and aminobenzene refer to C₆H₅NH₂, not the benzyl compound.

Not quite — the answer is B.

Ethanamine has the two-carbon ethane backbone with NH₂ as the principal group. CH₃NH₂ is methanamine; (CH₃)₂NH is N-methylmethanamine; CH₃CH₂CH₂NH₂ is propan-1-amine.

Not quite — the answer is B.

When NH₂ is the principal functional group, IUPAC uses the suffix -amine (e.g., ethanamine). If a higher-priority group like –COOH is present, NH₂ is expressed as the prefix amino- instead.