Which of the followig ions will finally give a black precipitate with `Ag^(o+)` ion?

Options

A. `SO_(3)^(2-)`
B. `Br^(-)`
C. `CrO_(4)^(2-)`
D. `S_(2)O_(3)^(2-)`

Answer

D

Explanation

`2Ag+S_(2)O_(3)^(2-)rarrAg_(2)S_(2)O_(3)`, white ppt which readily changes to yellow, orange, brown and finally black due to the formation of silver sulphide.
`Ag_(2)S_(2)O_(3)+H_(2)OrarrH_(2)SO_(4)+Ag_(2)S ("black")`