Answer: C, D
pKb different between I and II is 0.53 and that of III and IV is 4.6.
So option (B) is incorrect
Correct Statement (C), (D)
The most basic compound in the given option is (II) and least basic compound is (III)
In 2,4,6-trinitro aniline (III) due to strong –R effect of –NO2 groups, the \(\ell\).p. of –NH2 is more involved with benzene ring hence it has least basic strength.
Whereas (IV) N,N-Dimethyl 2,4,6-trinitro aniline, due to steric inhibition to resonance (SIR) effect; the lone pair of nitrogen is not in the plane of benzene, hence make it (\(\ell\).p.) more free to protonate