The solubility product of a soluble salt `A_(x)B_(y)` is given by: `K_(SP)= [A^(y+)]^(x) [B^(x-)]^(y)`. As soon as the product of concentration of `A^(y+)` and `B^(x-)` increases than its `K_(SP)`, the salt start precipitation. It may practically be noticed that AgCI is more soluble in water and its solublity decreases dramatically in `0.1M NaCI` or `0.1M AgNO_(3)` solution. It may therefore be conncluded that in presence of a common ion, the solubiolity of salt decreases.
The pH of a saturated solution of `Mg(OH)_(2)` is: `(K_(SP) of Mg(OH)_(2)= 1xx10^(-11))`

Options

A. 9
B. `3.87`
C. `10.43`
D. 5

Answer

C

Explanation

`Mg(OH)_(2)hArr underset(S)(Mg^(2+))+underset(2S)(2OH^(-)) (K_(SP)=4S^(3))`
`[OH^(-)]=2S=2xx3sqrt((K_(SP))/(4))`
`= 2xx3sqrt((1xx10^(-11))/(4))`
`=2xx1.36xx10^(-4)= 2.72xx10^(-4)`
`:. pOH = 3.565`
`:. pH=10.435`