Chemistry - GOC Question with Solution | TestHub

In benzylamine the NH₂ group is separated from the ring by a CH₂, so its lone pair is fully available (conjugate acid pKa ≈ 9.3). In aniline the lone pair delocalises into the ring (pKaH ≈ 4.6); p-nitroaniline is weaker still (the nitro group pulls the lone pair in further, pKaH ≈ 1); and in acetanilide the lone pair is tied up by the adjacent carbonyl (essentially non-basic). Benzylamine is the most basic.