A metal nitrate reacts with `KI` to give a black precipitate which on addition of excess of `KI` convert into orange colour solution. The cation of metal nitrate is

Options

A. `Hg^(2+)`
B. `Bi^(3+)`
C. `Pb^(2+)`
D. `Cu^(+)`

Answer

B

Explanation

`Bi^(3+)+KI rarr underset(("Black"))(BiI_(3))darr overset(KI)rarr underset(("Orange"))(K[BiI_(4)])`