An aqueous solution contains `0.10 M H_(2)S` and 0.20 M HCl. If the equilibrium constants for the formation of `HS^(–)` from `H_(2)S` is `1.0xx10^(–7)` and that of `S^(2-)` from `HS^(–)` ions is `1.2xx10^(–13)` then the concentration of `S^(2-)` ions in aqueous solution is

Options

A. `5xx10^(-19)`
B. `5xx10^(-8)`
C. `3xx10^(-20)`
D. `6xx10^(-21)`

Answer

C