$4.$ Hydrogen sulfide $($H$2$S$)$ is an odorous gas that can be stripped from solution in a process similar to that described in Example $2\mathrm{.}8$ for ammonia. The reaction is

with equilibrium constant K $=0\mathrm{.}86$ x $107.$ Find the fraction of hydrogen sulfide in H$2$S form at pH $6$ and pH $8.$