Gradual addition of KI solution to `Bi(NO_(3))_(3)` solution initially produces a dark brown precipitate which dissolves in excess of KI to give a clear yellow solution. Write the chemical equations for the above reactions.

Explanation

`Bi(NO_(3))_(3)` undergoes hydrolysis to produce nitric acid. `HNO_(3)` oxidises KI to `I_(2)` which is obtained as a brown precipitate. The precipitated `I_(2)` dissolves in excess of KI solution and forms a yellow coloured solution of the complex salt `KI_(3)` . The reactions involved are as follows:
`Bi(NO_(3))_(3) + H_(2)OtoBi(OH)(NO_(3)_(2) + HNO_(3)`
`6KI+8HNO_(3)to6KNO_(3)+underset("(brown ppt.)")(2NO+3I_(2)+4H_(2)O)`
`KI+I_(2)hArrKI_(3)`(yellow solution)