If the $k_{sp}$ of radium sulfate , $RaSO_4$ is $4 \times 10^{-11}$, Calculate the solubility of the compound in pure water. Let x = moles of $RaSO_4$ that dissolve per liter of water. Then , in the saturated solution ,

Question

$\begin{array}{1 1} (a)\; 6 \times 10^{-6}\;mol/L \\ (b)\; 5 \times 10^{-6}\;mol/L \\ (c)\; 7 \times 10^{-6}\;mol/L \\ (d) \;9\times 10^{-6}\;mol/L \end{array} $