The solubility of calcium carbonate at 298 K is $6.4 \times 10^{-5} \mathrm{~mol} \mathrm{dm}^{-3}$. Calculate the value of solubility product at the same temperature?

The solubility product of $\mathrm{PbI}_2$ is $1.08 \times 10^{-7}$.

Calculate its solubility in $\mathrm{mol} \mathrm{dm}^{-3}$ at 298 K .

What is the value of pH of a NaOH solution that dissociates $2 \%$ in its 0.01 M solution?

Which among the following salts turns red litmus blue in its aqueous solution?