The solubility of a salt $M_2X_3$ is $y \ mol \ m^{-3}$. Its solubility product is:

The solubility product $({K_{sp}})$ of $BaCO_3$ is $1.5 \times 10^{-9}$. At what concentration of $Ba^{2+}$ ions will precipitation begin when solid $Ba(NO_3)_2$ is added to a $10^{-4} \ M$ solution of $Na_2CO_3$?

If the concentration of $Cr_2O_7^{2-}$ in a saturated solution of $Ag_2Cr_2O_7$ is $6.5 \times 10^{-5} \ M$ at a constant temperature,calculate the value of $K_{sp}$ for $Ag_2Cr_2O_7$.

What is the $pH$ of a saturated solution of $Cu(OH)_2$? $(K_{sp} = 4.0 \times 10^{-6})$

For the following Assertion and Reason,the correct option is
Assertion $(A) :$ When $Cu^{2+}$ and sulphide ions are mixed,they react together extremely quickly to give a solid.
Reason $(R) :$ The equilibrium constant of $Cu^{2+}_{(aq)} + S^{2-}_{(aq)} \rightleftharpoons CuS_{(s)}$ is high because the solubility product is low.

Which of the following represents the correct solubility product expression for calcium phosphate?