What is the correct order of basicity of aliphatic amines purely on the basis of solvation effect of the ammonium cation?

1° > 2° > 3° 2° > 1° > 3° 2° > 3° > 1° 3° > 2° > 1°

1° > 2° > 3°

In aqueous phase, the greater the size of the ion, lesser will be the hydration and less stabilized is the ion. Since the stability of ions is directly proportional to the basic strength of amines, primary amines will be the most basic and tertiary amines will be the least basic. This order is completely opposite to that based on the inductive effect of alkyl groups.