Ionisation constant of a weak base MOH, is given by the expression
`K_(b)=([M^(+)][OH^(-)])/([MOH])`
Values of ionisation constant of some weak bases at a particular temperature are given below :
`underset(K_(b))(Base)" "underset(5.4xx10^(-4))("Dimethylamine")" "underset(1.3xx10^(-14))(H_(2)O(l))" "underset(1.77xx10^(-9))("Pyridine")" "underset(1.77xx10^(-5))("Ammonia")`
Arrange the bases in decreasing order of the extent of their ionisation at equilibrium. Which of the above base is the strongest?

Explanation

Greater the ionization constant `(K_(b))` of a base, greater is the ionization of the base. Hence, order of ionization will be
`{:(,"Dimethylamine",gt,"Ammonia",gt,"Pyridine",gt,"Urea",),(K_(b),5.4xx10^(-4),,1.77xx10^(-5),,1.77xx10^(-9),,1.3xx10^(-14),):}`