Calculate the $$\mathrm{pH}$$ of a buffer solution containing $$0.01 ~\mathrm{M}$$ salt and $$0.004 \mathrm{~M}$$ weak acid.

$$\left(\mathrm{pK}_{\mathrm{a}}=4.762\right)$$

Calculate the concentration of $$\mathrm{H}^{+}$$ ions in a solution if pOH is 11.

Acetic acid dissociated to $$1.20 \%$$ in its $$0.01 \mathrm{~M}$$ solution. What is the value of its dissociation constant?

Find solubility of $$\mathrm{PbI}_2$$ if its solubility product is $$7.0 \times 10^{-9}$$.