Arrange the following amines in the decreasing order of basicity.

${\mathrm{K}}_{\mathrm{b}}$ Values are a measure of basicity. Higher the ${\mathrm{K}}_{\mathrm{b}}$ value, greater will be basicity.

(I) Basic character  $\mathrm{\alpha }\frac{1}{\mathrm{\%}\text{\hspace{0.17em}s-\hspace{0.17em}character}}$

$\mathrm{N}-{\mathrm{sp}}^2$ has more % s-character than $\mathrm{N}-{\mathrm{sp}}^3$ so it is less basic as compare to $\mathrm{N}-{\mathrm{sp}}^3$ Hence $\mathrm{I}\mathrm{I}\mathrm{I}>\mathrm{I}.$

(II) In the (ii) structure lone pair present on the N atom is involved in aromaticity so, it is difficult to donate. Hence, least basic

Thus, the correct order will be: $\mathrm{I}\mathrm{I}\mathrm{I}>\mathrm{I}>\mathrm{I}\mathrm{I}$