Question

explain the basicity of amines in gaseous phase as well as in aqueous phase

Answer 1

Tertiary amines are weak bases due to the steric bulk of its three alkyl groups , which prevent the attack to the H+, and even if protonation occurs, remeber that there is no H left for a hydrogen-bond in the 3° amine molecule: no hydrogen-bond, no stabilization of the produced ammonium ion.

Ammonia is less basic than the other amines because the atoms surrounding the N (which after protonation will bear a postive-one formal charge) are all hydrogens and they do very little to stabilize its +ve charge...therefore it'd be less stable than the ammonium ions produced by the other amines