Alkyl amines are stronger bases than aryl amines. Justify.

Explanation

(a) Aniline may be regarded as a resonance hybrid of the following five contributing structures (I-V).

Due to resonance, the lone pair of electro on the nitrogen atom gets delocalised over the benzene ring and thus it is less easily available for protonation. At the sametime nitrogen acquires some positive charge (II to IV) and this repels the incoming proton.
On the other hand in ethylamine, the delocalisation of lone pair of electrons on the nitrogen atom by resonance is not possible. Moreover the electron density on the nitrogen increased by the electron releasing inductive effect (+ I effect) of ethyl group.

Hence aniline is weaker base than ethylamine.