On adding 0.1 M solution each of `Ag^(+),Ba^(2+), Ca^(2+)` ions in a `Na_(2)SO_(4)` solution, species first precipitated is `(K_(sp)BaSO_(4)=10^(-11),K_(sp)CaSO_(4)=10^(-6),K_(sp) Ag_(2)SO_(4)=10^(-5))`

Options

A. `Ag_(2)SO_(4)`
B. `BaSO_(4)`
C. `CaSO_(4)`
D. all of these

Answer

B

Explanation

`K_(sp)` for `Ag_(2)SO_(4)=[Ag^(+)]^(2)[SO_(4)^(2-)]`
`:. [SO_(4)^(2-)]` for precipitation of `Ag_(2)SO_(4) lt (K_(sp))/([Ag^(+)]^(2))=(10^(-5))/((0.1)^(2))=10^(-3)M`
Similarly, `[SO_(4)^(2-)]` for precipitation of `BaSO_(4) lt (K_(sp))/([Ba^(2+)])=(10^(-11))/(0.1)=10^(-10)M`
`[SO_(4)^(2-)]` for precipitation of `CaSO_(4) lt (K_(sp))/([Ca^(2+)])=(10^(-6))/(0.1)=10^(-5)M`
Thus, minimum `[SO_(4)^(2-)]` reuired for precipitaion is for `BaSO_(4)`.