In the following compounds the order of basicity is :
In the following compounds
the order of basicity is :
$\mathrm{IV}>\mathrm{I}>\mathrm{III}>\mathrm{II}$
$\mathrm{III}>\mathrm{I}>\mathrm{IV}>\mathrm{II}$
$\mathrm{II}>\mathrm{I}>\mathrm{III}>\mathrm{IV}$
$\mathrm{I}>\mathrm{III}>\mathrm{II}>\mathrm{IV}$
Solution
In (I) the unshared pair of electrons on $\mathrm{N}$ always available for protonation in (III) due to presence of electronegative $\mathrm{O}$ atom the electron density on $\mathrm{N}$ is decreased. In (IV) resonance suppresses the basic character.