Answer : The concentration of hydrogen ion at equilibrium is 0.118 M
Solution : Given,
Concentration (c) = 0.200 M
Equilibrium constant =

The equilibrium reaction is,

initially conc. c 0 0
At eqm.

First we have to calculate the concentration of value of dissociation constant
.
Formula used :

Now put all the given values in this formula ,we get the value of dissociation constant
.

By solving the terms, we get

Now we have to calculate the concentration of hydrogen ion at equilibrium.
![[H^+]=c\alpha=0.200* 0.59=0.118M](https://img.qammunity.org/2020/formulas/chemistry/college/ftlaso52fbh8zgjozr84ro81fooiowjxxb.png)
Therefore, the concentration of hydrogen ion at equilibrium is 0.118 M