Q . ARRANGE THE FOLLOWING IN THE INCREASING ORDER OF BASICITY-

For determining the basic strength, always REMEMBER THAT MORE IS THE TENDENCY TO DONATE ELECTRON, STRONGER THE ACID i.e. we should analyse them on the basis of lewis base(and for acidic strength deprotonate and think about the stability of this conjugate base, more it is stable, more its acidic character; so here think about Brnsted-Lowry acid).
NH2 group is more basic than OH group.so (IV) is the most basic among them.
For (i), NO2 is highle elctronegative and so withdraw the electron strongly and so is the least basic.
So the order should be:
(IV)>(II)>(III)>(I)

Approved