At 298 K pH of a solution is 13 . What is the number of $\mathrm{H}_3 \mathrm{O}^{+}$ions present in one mL of this solution?

The solubility product of $\mathrm{PbI}_2$ is $2.8 \times 10^{-8}$. Calculate its solubility in $\mathrm{mol} \mathrm{dm}^{-3}$.

Which from the following buffers is used for precipitation of cations of IIIA group in qualitative analysis?

The dissociation constant of weak monoacidic base is $1.8 \times 10^{-5}$. Calculate the degree of dissociation in 0.02 M solution.