for example if any compound there is presence of resonance it decreases basic nature of compound so that aromatic amines are less basic than aliphatic amines C₆H₅NH₂ is less basic than C₂H₅NH₂.if we consider RCONH₂ amide with resonance these are less basic than aliphatic amines.in some molecule there is cross conjugation which increses basic nature of compound for example NH₂CONH₂ is more basic than RCONH₂ while C₆H₅CONH₂ is more basic than CH₃CONH₂.