For the precipitation of $AgCl$ by $Ag^{+}$ ions and $HCl$,which of the following is true?

How many grams of $CaC_2O_4$ (molecular weight $= 128$) on dissolving in $1 \ L$ of distilled water will give a saturated solution? $[K_{sp}(CaC_2O_4) = 2.5 \times 10^{-9} \ mol^2 L^{-2}]$

The solubility of calcium carbonate $(CaCO_3)$ at $298 \ K$ is $6.4 \times 10^{-5} \ mol \ dm^{-3}$. Calculate the value of solubility product $(K_{sp})$ at the same temperature.

Calculate the solubility product of sparingly soluble salt $BA$ at $300 \ K$ if its solubility is $9.1 \times 10^{-3} \ mol \ dm^{-3}$ at same temperature.

If the solubility of a sparingly soluble salt of the type $BA_2$ (giving three ions on dissociation of a molecule) is $x \ mol \ L^{-1}$,then its solubility product is given by

Which of the following would increase the solubility of $Pb(OH)_2$?