When a salt of weak acid and weak base is dissolved in water at 25ºC, the pH of the resulting solution will always :-be 7be greater than 7be less than 7depend upon Ka and Kb values

The pH of a solution resulting from a salt of a weak acid and weak base dissolved in water at 25ºC will depend upon the Ka (acid dissociation constant) and Kb (base dissociation constant) values.

Here's why:

1. When a salt of a weak acid and weak base is dissolved in water, it will undergo hydrolysis. This means that the ions of the salt will react with water to form the weak acid and weak base.

2. The extent to which this reaction occurs depends on the relative strengths of the weak acid and weak base, which are determined by their Ka and Kb values.

3. If Ka > Kb, the weak acid is stronger than the weak base, and the solution will be acidic, so the pH will be less than 7.

4. If Ka < Kb, the weak base is stronger than the weak acid, and the solution will be basic, so the pH will be greater than 7.

5. If Ka = Kb, the weak acid and weak base are equally strong, and the solution will be neutral, so the pH will be 7.

So, the pH of the solution does not always have a fixed value, but rather, it depends on the Ka and Kb values of the weak acid and weak base.