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

(i) Order of extent of ionisation at equilibrium is : Dimethylamine > Ammonia > Pyridine > Urea
(ii) Since dimethylamine will ionise to the maximum extent it is the strongest base.