At $30° \mathrm{C}$ the solubility of ${\mathrm{Ag}}_2{\mathrm{CO}}_3\left(K_{sD}=8\times {10}^{-12}\right)$would be greatest in one litre of:

Solubility decreases in the presence of a common ion.

Ions for a given molecule,

${\mathrm{Ag}}_2{\mathrm{CO}}_3\rightleftharpoons 2{\mathrm{Ag}}^{+}+{\mathrm{CO}}_3^{2-}$

At $30° \mathrm{C}$ the solubility of ${\mathrm{Ag}}_2{\mathrm{CO}}_3\left(K_{sD}=8\times {10}^{-12}\right)$ would be greatest in one litre of pure water.