Question

In a saturated solution of calcium phosphate, the concentration of `PO_(4)^(-3)` ions is `3.3xx10^(-7)`. The `K_(sp)` of `Ca_(3)(PO_(4))_(2)` will be
A. (a)`1.32xx10^(-31)`
B. (b)`1.32xx10^(-32)`
C. (c )`1.32xx10^(-33)`
D. (d)`1.32xx10^(-33)`

Answer 1

Correct Answer - B
`[PO_(4)^(-3)]=3.3xx10^(-7)M`
`[Ca^(2+)]=3/2xx[PO_(4)^(-3)]=3/2xx3.3xx10^(-7)=5xx10^(-7)M`
`K_(sp)Ca_(3)(PO_(4))_(2)=[ca^(2+)]^(3)[PO_(4)^(-3)]^(2)`
`implies (5xx10^(-7))^(3)(3.3xx10^(-7))^(2)=1.32xx10^(-32)`