Chemistry - GOC Question with Solution | TestHub

Ethylamine is a standard aliphatic amine (conjugate acid pKa ≈ 10.6). In aniline (A) the nitrogen lone pair is delocalised into the benzene ring, so it is a much weaker base (pKaH ≈ 4.6). The amidine (B) and guanidine (C) are far stronger bases than ethylamine because their conjugate acids are resonance-stabilised over two or three nitrogens, and piperazine (D) is an ordinary aliphatic diamine comparable to ethylamine.