The dissociation of silver oxalate ($Ag_2C_2O_4$) in aqueous solution is given by the equation: $Ag_2C_2O_4(s) \rightleftharpoons 2Ag^+(aq) + C_2O_4^{2-}(aq)$ From the stoichiometry of the reaction, if $S$ is the molar solubility of $Ag_2C_2O_4$, then: $[Ag^+] = 2S$ and $[C_2O_4^{2-}] = S$ Given that the concentration of $Ag^+$ ions is $2.2 \times 10^{-4}\text{ M}$: $2S = 2.2 \times 10^{-4}\text{ M}$ $S = 1.1 \times 10^{-4}\text{ M}$ Therefore, the concentration of oxalate ions is $[C_2O_4^{2-}] = 1.1 \times 10^{-4}\text{ M}$. The solubility product constant ($K_{sp}$) is expressed as: $K_{sp} = [Ag^+]^2[C_2O_4^{2-}]$ Substitute the given values into the $K_{sp}$ expression: $K_{sp} = (2.2 \times 10^{-4})^2 \times (1.1 \times 10^{-4})$ $K_{sp} = (4.84 \times 10^{-8}) \times (1.1 \times 10^{-4})$ $K_{sp} = 5.324 \times 10^{-12} \approx 5.3 \times 10^{-12}$