A solution saturated in lime water has a `pH` fo `12.4`. Then the `Ksp` for `Ca(OH)_(2)` is `-`

Options

A. `3.2xx10^(-3)`
B. `7.8xx10^(-6)`
C. `7.8xx10^(-28)`
D. `3.2xx10^(-4)`

Answer

2

Explanation

`Ph=12.4" "rArr" "-log(h+)=12.4rArr`
`log[H^(+)]=13.6" "Ca(overset(+)(OH))_(2)hArr 2OH+Ca^(2+)`
`[H^(+)]=4xx10^(-13)`
`[OH^(-)]=(10^(-14))/(4xx10^(-13))=(1)/(4)=2.5xx10^(-2)`
`ksp=[Ca^(2+)][OH^(-)]" "[Ca^(2+)]=(1)/(2)[OH^(-)]rArr((1)/(8)xx10^(-1))((1)/(4)xx10^(-1))^(2)=(1)/(8)xx(1)/(16)xx10^(-3)=7.8xx10^(-6)Ans.`