The solubility product of strontium fluoride is `8.0xx10^(-11)`. At what concentration of `Sr^(2+)` ion the precipitation of strontium fluoride would start from a solution containing `0.01 M F^(-)` ion ?

Options

A. `8.xx10^(-9)M`
B. `8xx10^(-13)M`
C. `8.0xx10^(-7)M`
D. `1.25xx10^(-9)M`

Answer

C

Explanation

`K_(sp)=[Sr^(2+)][F^(-)]^(2)`
`[Sr^(2+)](0.01)^(2)=8.0xx10^(-11)`
`therefore [Sr^(2+)]=8.0xx10^(-7)M`