1. Consider a reaction between strong acid HCl and a weak base NH4OH to produce a salt NH4CI and water
2. NH4 is a strong conjugate acid of the weak base NH4OH and it has a tendency to react with OH- from water to produce unionised NH4 as below,
3. There is no such tendency shown by Cl- and therefore [H+] > [OH-] the solution is acidic and the pH is less than 7.
4. In the salt hydrolysis of strong base and weak acid, we have to derive a relationship between Kh and Kb as Kh . Kb = Kw