The sulphide ion concentration `[S^(2-)]` in saturated `H_(2)S` solution is `1xx10^(-22)`. Which of the following sulphides should be quantitavely precipitated by `H_(2)S` in the presence of dil. `HCl`?
`{:("Sulphide",,"Solubility Product"),((I),,1.4xx10^(16)),((II),,1.2xx10^(-22)),((III),,8.2xx10^(-46)),((IV),,5.0xx10^(-34)):}`

Options

A. `I`,`II`
B. `III`,`IV`
C. `II`,`III`,`IV`
D. Only `I`

Answer

B

Explanation

Basic radicals of groups `II` and `IV` are precipitated by `H_(2)S` in the form of their sulphides. Second group in acidic ,medium and fourth group in alkaline medium. They precipitate when ionic product is more than solubility product.