Which of the following statement (s) is/are correct among the options given.

$\mathrm{pH}={\mathrm{pK}}_{\mathrm{a}}+\log \frac{\left[\text{ Salt }\right]}{\left[\text{ Acid }\right]},pOH=p{K}_b+\log \frac{\left[\text{ Salt }\right]}{\text{ [Base }]}$

Thus as salt concentration decreases for acidic buffers, so $pH$ decreases. Statement (a) is correct, Thus as salt  decreases, Choice (b) is correct. For any salt when $Q=K_{sp}$

Hence the solution is saturated. Hence choice (c) is correct.

The solubility product is for all salts. choice (d) is Incorrect.