Answer : The concentration of
at equilibrium will be, 
Explanation : Given,
Equilibrium constant = 
Initial concentration of
= 0.100 M
Initial concentration of
= 0.100 M
Initial concentration of
= 0.00 M
The balanced equilibrium reaction is,

Initial conc. 0.1 0.1 0
At eqm. (0.1-2x) (0.1+2x) x
The expression of equilibrium constant for the reaction will be:
![K_c=\frac{[H_2]^2[S_2]}{[H_2S]^2}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BH_2%5D%5E2%5BS_2%5D%7D%7B%5BH_2S%5D%5E2%7D)
Now put all the values in this expression, we get :

By solving the term 'x' by quadratic equation, we get two value of 'x'.

Concentration of
at equilibrium = 
Therefore, the concentration of
at equilibrium will be, 