`HgCl_(2)` and `I_(2)` both when dissolved in water containing `I^(-)` ions the pair of species formed is:

Options

A. `HgI_(2)^(-), I_(3)^(-)`
B. `HgI_(2),I^(-)`
C. `HgI_(4)^(2-),I_(3)^(-)`
D. `Hg_(2)I_(2),I^(-)`

Answer

C

Explanation

`I_(2)` reacts with `I^(-)` and maintains the following equilibrium.
`I_2 + I^(-) hArr I_2^(-)`
`Hg^(2+)` gives ppt. of `Hgl_2` on reaction with `I^-` but `HgI_2` is soluble in solution of `I^-`
`Hg^(2+) + 2I^(-) to HgI_2`
`HgI_2 + 2I^(-) hArr [HgI_4]^(2-)`