Rank the amines in each set in order of increasing basicity.

The lone pair present on nitrogen atom makes the nitrogen in amines electron dense. Greater the lone pair availability on nitrogen atom to donate to other species, more will be its basicity. Basicity of nitrogen atom will decrease if lone pair is not available for donation to other species as in case of aromatic species, the lone pair is delocalised in the ring and not available for donation to other species. Amides are less basic than amines due to delocalisation of the lone pair of nitrogen towards the carbonyl group present adjacent to it.

The aliphatic amine will be the strongest base followed by aniline as nitrogen in aliphatic amine is ${\mathrm{sp}}^3$hybridised whereas in aniline, nitrogen is ${\mathrm{sp}}^2$hybridised. Hold of electrons towards nucleus will be more in case of ${\mathrm{sp}}^2$nitrogen and thus lone pair donating ability decreases. Basicity of nitrogen will be least when its lone pairs are shared in two rings instead of one as lone pair availability decreases to a higher extent and thereby the order of basicity looks like as follows,

The lone pair present on nitrogen atom makes the nitrogen in amines electron dense. Greater the lone pair availability on nitrogen atom to donate to other species, more will be its basicity. Basicity of nitrogen atom will decrease if lone pair is not available for donation to other species as in case of aromatic species, the lone pair is delocalised in the ring and not available for donation to other species. Amides are less basic than amines due to delocalisation of the lone pair of nitrogen towards the carbonyl group present adjacent to it.

In part (b), aliphatic amine will be the strongest base and least basic will be substituted pyrrole as if nitrogen donates its lone pair, the aromaticity will be lost in pyrrole ring and this will lead to highly unstable system. Thus, pyrrole will not donate the lone pair.

The lone pair present on nitrogen atom makes the nitrogen in amines electron dense. Greater the lone pair availability on nitrogen atom to donate to other species, more will be its basicity. Basicity of nitrogen atom will decrease if lone pair is not available for donation to other species as in case of aromatic species, the lone pair is delocalised in the ring and not available for donation to other species. Amides are less basic than amines due to delocalisation of the lone pair of nitrogen towards the carbonyl group present adjacent to it.

In part (c), aliphatic amine will be the strongest base and least basic will be substituted pyrrole as if nitrogen donates its lone pair, the aromaticity will be lost in pyrrole ring and this will lead to highly unstable system. Thus, pyrrole will not donate the lone pair.

The lone pair present on nitrogen atom makes the nitrogen in amines electron dense. Greater the lone pair availability on nitrogen atom to donate to other species, more will be its basicity. Basicity of nitrogen atom will decrease if lone pair is not available for donation to other species as in case of aromatic species, the lone pair is delocalised in the ring and not available for donation to other species. Amides are less basic than amines due to delocalisation of the lone pair of nitrogen towards the carbonyl group present adjacent to it.

In part (d), the electron releasing group will increase the basicity of the compound and electron withdrawing group will decrease the basicity of the compound. The ethyl group acts as electron donating group while acetoxy group acts as a electron withdrawing group. Hence, the basicity order will be,

The lone pair present on nitrogen atom makes the nitrogen in amines electron dense. Greater the lone pair availability on nitrogen atom to donate to other species, more will be its basicity. Basicity of nitrogen atom will decrease if lone pair is not available for donation to other species as in case of aromatic species, the lone pair is delocalised in the ring and not available for donation to other species. Amides are less basic than amines due to delocalisation of the lone pair of nitrogen towards the carbonyl group present adjacent to it.

In part (e), amides are least basic due to involvement of the lone pair of nitrogen in delocalisation with adjacent carbonyl group. Aliphatic amine will be the strongest basic then aniline as in aniline the lone pair is delocalised in the ring making the less availability of lone pair.