NEET Chemistry: Nomenclature classification structure basic character and identification of amines Practice Questions

Correct answer: C — Primary > Secondary > Tertiary

Alkyl groups donate electron density to the nitrogen, increasing its basicity. The order of basicity is Tertiary amine > Secondary amine > Primary amine > Ammonia (NH₃).

Correct answer: A — (ii)-Secondary amine

The compound CH₃CH₂NHCH₃ has one N-H bond and is bonded to two alkyl groups (ethyl and methyl). This classification defines it as a secondary amine.

Correct answer: A — CH₃NHCH₃

A secondary amine has one alkyl group and one hydrogen atom attached to the nitrogen atom (R₂NH). CH₃NHCH₃ fits this definition.

Correct answer: D — Amines with two alkyl groups and one H on the N

Secondary amines are those where the nitrogen atom is bonded to two alkyl groups and one hydrogen atom.

Correct answer: C — Ethanamine

The parent chain is ethyl (2 carbons), and the functional group is amine. Therefore, the name is Ethanamine.

Correct answer: C — Higher basicity

Amines possess a lone pair of electrons on the nitrogen atom, allowing them to act as a base (higher basicity). Alcohols primarily exhibit hydrogen bonding with oxygen.

Correct answer: D — Butylamine

The compound has a four-carbon chain with a primary amine functional group (NH₂). The corresponding name is Butylamine.

Correct answer: B — Diethylamine

Alkyl amines exhibit basicity due to the donation of lone pair electrons. The basicity generally increases with the increase in alkyl substitution on the nitrogen atom (more electron-donating groups). Thus, tertiary amines are generally the strongest bases in this comparison.

Correct answer: C — (i)-Propylamine

The reaction of an aldehyde (propanal) with ammonia (NH₃) results in a primary amine. The resulting amine is CH₃CH₂CH₂NH₂, which is named Propylamine.

Correct answer: D — (iii)-N-methylpropan-2-amine

Tertiary amines (R₃N) are generally weaker bases than primary or secondary amines because the lone pair on nitrogen is less available for donation to a proton; this is due to less effective inductive donation from the alkyl groups.

Correct answer: A — Primary amine

In CH₃NH₂, the nitrogen atom is bonded to one methyl group and two hydrogen atoms, which defines it as a primary amine.

Correct answer: A — Methylamine

Methylamine (CH₃NH₂) is a primary amine because the nitrogen atom is bonded to only one alkyl group and two hydrogen atoms.

Correct answer: D — (iii) Diethylamine

Diethylamine has two ethyl groups attached to the nitrogen atom, making it the most substituted among the options, thus generally exhibiting the highest basic character compared to the mono-substituted methylamine and ethylamine.

Correct answer: D — (iii) (CH₃)₃N

The degree of alkyl substitution depends on the number of carbon atoms directly attached to the nitrogen atom. (CH₃)₃N has three methyl groups attached, making it a tertiary amine, which has the highest substitution among the choices.