From Example 9.4 in the context, the decreasing order of basic strength is established as: (C₂H₅)₂NH > C₂H₅NH₂ > NH₃ > C₆H₅NH₂. This shows secondary amines are more basic than primary amines in aqueous solution due to the interplay of inductive effect, solvation effect and steric hindrance. For (i), benzylamine (C₆H₅CH₂NH₂) is more basic than aniline because the -NH₂ group is not directly attached to the benzene ring, preventing lone pair delocalization. For (ii) and (iii), the context explains that for methyl and ethyl substituted amines in aqueous solution, the order follows: secondary > primary > tertiary. Aniline (C₆H₅NH₂) is the least basic in all cases due to resonance delocalization of the lone pair into the benzene ring.