One litre of a saturated solution of `CaCO_(3)` is evaporated to dryness due to which `7.0` mg of residue is left .
The solubility product for `CaCO_(3)` is

Options

A. `4.9 xx 10^(-8)`
B. `4.9 xx 10^(-5)`
C. `4.9 xx 10^(-9)`
D. `4.9 xx 10^(-7)`

Answer

3

Explanation

Moles of `CaCO_(3)` in the residue ` = (7 xx 10^(-3))/100 = 7 xx 10^(-5)`
Moles of `CaCO_(3)` in litre solution ` = 7 xx 10^(-5)`
`{:(CaCO_(3)(s)hArrCa^(2+) + CO_(3)^(2-)),(" "7 xx 10^(-5)" " 7 xx 10^(-5)):}`
`K_("sp") = [Ca^(2+)][CO_(3)^(2-)] = 7 xx10^(10^(-5))xx 7 xx 10^(-5) = 4.9 xx 10^(-9)`