Calculate the equilibrium concentration of $\mathrm{Pb}^{++}$ions in a solution of PbS containing $1 \times 10^{-11} \mathrm{~mol} \mathrm{dm}^{-3}$ of sulphide ions.

(Given $\mathrm{K}_{\mathrm{sp}}$ for $\mathrm{PbS}=8.0 \times 10^{-28}$ )

Which among the following salts forms basic solution in water?

A weak base is $5 \%$ dissociated in its 0.01 M solution. Calculate the dissociation constant.

Solubility of binary sparingly soluble salt is $1.12 \times 10^{-4} \mathrm{~g} / \mathrm{dm}^3$. Calculate its solubility product (molar mass of salt $=112 \mathrm{~g} \mathrm{~mol}^{-1}$ )