A white crystalline substance dissolves in water.On passing `H_(2)S` in this solution, a black precipitate is obtained.The black precipitate dissolves completely in hot `HNO_(3)`.On adding a few drops of concentrated `H_(2)SO_(4)`, a white precipitate is obtained which is soluble in ammonium acetate.The white precipitate is that of ,
A. `BaSO_(4)`
B. `SrSO_(4)`
C. `PbSO_(4)`
D. `Ag_(2)SO_(4)`
A. `BaSO_(4)`
B. `SrSO_(4)`
C. `PbSO_(4)`
D. `Ag_(2)SO_(4)`
Correct Answer – C
The white precipitate obtained with `H_(2)SO_(4)` is that of `PbSO_(4)`.The white crystalline substance may be that of `Pb(NO_(3))_(2)`.
`Pb^(2+)+S^(2+)to PbS darr (“black”),3PbS darr+8HNO_(3) to 3Pb^(2+)+6NO_(3)^(-) + 3S darr+2NO+4H_(2)O`
`Pb^(2+) +SO_(4)^(2-) to PbSO_(4) darr` (white)
`PbSO_(4)+2CH_(3)COONH_(4) to (CH_(3)COO)_(2)Pb+(NH_(4))_(2)SO_(4)`
`BaS` and `SrS` precipitates are not black in colour.`Ag_(2)SO_(4)` is white precipitate but does not dissolve in ammonium acetate.