`H_(2)S` is bubbled into 0.2 M NaCN solution which is 0.02 M in each `[Cd (CN ) _(4) ]^(2-) and [Ag (CN _(2)) ]^(-) H _(2)S` produces `1 xx10^(-9)M` sulphide ion in the solution Given, `K _(ap) Ag _(2) S =1 xx 10 ^(-50)M ^(3), K _(ap) Cd s=7.3 xx 10 ^(-18) M ^(2) K _("iost") [Ag (CN ) _(2) ]^(1) = 1 xx 10 ^(-20) M ^(2) .K _(iost) [Cd (CN ) _(4) ]^(2-) = 7.8 xx 10 ^(-18) M ^(1).` Identify the correct statement.

Options

A. `Ag _(2) S` Sprecipitates first from the solution
B. `A g _(2)` Sprecipitates at a sulphide concentration `1 xx 10 ^(15) M`
C. Cds precipitates first from the solution
D. None of them precipitates under the given conditions

Answer

C

Explanation

Ionic produect `gt K _(sp)` then ppt forms