Aniline is weaker as a base compared to ethylamine due to the aliphatic ethylamine having higher basicity owing to the greater availability of its lone pair electrons on the nitrogen atom.

p-methoxyaniline is a stronger base than aniline due to the electron-donating nature of the methoxy group, which increases the availability of lone pair electrons on the nitrogen atom, enhancing its basicity compared to aniline.

Aniline's resonance stabilization and electron delocalization within its aromatic ring reduce the availability of its lone pair, making it less basic than ammonia.