Basicity ∝ electron pair intensity on nitrogen. (III) Refer image 1 No resonance and + I effect from both sides ∴ most basic. (II) Refer image. 2 Nitrogen do not involve in resonance ∴ more basic. (I) Refer image.3 Nitrogen lone pair is involved in resonance. Therefore less available for donation. ∴ less basic. (IV) Refer image.4 6πe−, Aromatic nitrogen lone pair participating in aromaticity ∴ less available for donation. : least basic. ∴ III > II > I > IV (Basicity order)