Which of the following is most soluble in water?

Assign $A, B, C, D$ from the given type of reaction.
$SrC_2O_4(s) + 2HCl(aq) \longrightarrow SrCl_2(aq) + H_2C_2O_4(aq)$

The solubility product of a sulphide $MS$ is $3 \times 10^{-25}$ and that of another sulphide $NS$ is $4 \times 10^{-40}$. In an ammoniacal solution,which of the following occurs?

In qualitative analysis,the metals of group $I$ can be separated from other ions by precipitating them as chloride salts. $A$ solution initially contains $Ag^{+}$ and $Pb^{2+}$ at a concentration of $0.10 \, M$. Aqueous $HCl$ is added to this solution until the $Cl^{-}$ concentration is $0.10 \, M$. What will the concentrations of $Ag^{+}$ and $Pb^{2+}$ be at equilibrium? ($K_{sp}$ for $AgCl = 1.8 \times 10^{-10}$,$K_{sp}$ for $PbCl_2 = 1.7 \times 10^{-5}$)

Which of the following has the minimum solubility in water?

The solubility of $Ca(OH)_{2}$ is $s \ mol \ L^{-1}$. The solubility product $(K_{sp})$ under the same condition is: