Question:
An aqueous solution contains $0.10 \mathrm{M} \mathrm{H}_{2} \mathrm{~S}$ and $0.20 \mathrm{M} \mathrm{HCl}$. If the equilibrium constants for the formation of $\mathrm{HS}^{-}$from $\mathrm{H}_{2} \mathrm{~S}$ is $1.0 \times 10^{-7}$ and that of $\mathrm{S}^{2-}$ from $\mathrm{HS}^{-}$ions is $1.2 \times 10^{-13}$ then the concentration of $S^{2-}$ ions in aqueous solution is :
Correct Option: 1
Solution:
