The solubility products of three sparingly soluble salts $AB$,$A_2B$ and $AB_3$ are respectively $4.0 \times 10^{-20}$,$3.2 \times 10^{-11}$ and $2.7 \times 10^{-31}$. The increasing order of their solubility is

Increasing order of solubility of $AgCl$ in $(i) H_2O$, $(ii) 1 \ M \ NaCl \ (aq.)$, $(iii) 1 \ M \ CaCl_2 \ (aq.)$ and $(iv) 1 \ M \ NaNO_3 \ (aq.)$ solution.

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:

$A$ $1.0 \ L$ of aqueous solution contains $1 \times 10^{-8} \ M \ NaBr$,$1 \times 10^{-8} \ M \ NaCl$ and $1 \times 10^{-8} \ M \ NaI$. To this solution,$1 \times 10^{-10} \ M$ aqueous $AgNO_3$ solution is added dropwise. The order of precipitation of $AgX$ $(X = Cl, Br, I)$ is:
$(K_{sp}(AgCl) = 1.8 \times 10^{-10}; K_{sp}(AgBr) = 5 \times 10^{-13}; K_{sp}(AgI) = 8.3 \times 10^{-17})$

The solubility of $AgCN$ increases on adding $KCN$ due to the formation of .......

The $K_{sp}$ of $AgCl$ is $1.8 \times 10^{-10}$. The concentration of $Cl^-$ required to initiate the precipitation of $AgCl$ in a solution containing $4 \times 10^{-3} \ M \ Ag^+$ is: