Account for
i) Reduction of CH3CN gives CH3CH2NH2 while CH3NC gives (CH3)2NH.
ii) (CH3)2NH requires two molar proportion of CH3I to give the same crystalline product formed by (CH3)2N with one mole of CH3I.
iii) Nitration of aniline with conc.HNO3 may end up with same meta nitro product.
iv) p-toluidine is a stronger base than p-nitroaniline.