Question

The increasing order of basicity of the following compounds is : 

(1) (b) < (a) < (c) < (d)
(2) (b) < (a) < (d) < (c)
(3) (d) < (b) < (a) < (c)
(4) (a) < (b) < (c) < (d)

Answer 1

Ans. (2)

Order of base nature depends on electron donation tendency. 

In compound  nitrogen is sp² hybridized so least basic among all given compound.
compound  is very strong nitrogeneous organic base as lone pair of one nitrogen delocalize in resonance and make another nitrogen negatively charged and conjugate acid have two equivalent resonating structure.

Thus it is most basic in given compounds.