Which of the following is a sparingly soluble salt?

The $K_{sp}$ for bismuth sulphide $(Bi_{2}S_{3})$ is $1.08 \times 10^{-73}$. The solubility of $Bi_{2}S_{3}$ in $mol \ L^{-1}$ at $298 \ K$ is ......

At $298 \ K$ temperature,the solubility product $(K_{sp})$ for $AgCl$ is $1.5 \times 10^{-10}$. Calculate its solubility in $g \ L^{-1}$ in pure water. (Molar mass of $AgCl = 143.5 \ g \ mol^{-1}$)

Precipitation occurs if the ionic product is ........

The salt having the least solubility in water is

If the solubility product constant $(K_{sp})$ of $Ni(OH)_2$ is $1.9 \times 10^{-15}$,the molar solubility of $Ni(OH)_2$ in $1.0 \ M \ NaOH$ is: