$($b$)$ A $2\mathrm{.}0c{m}^2$ area of water$-$ hexanol interface was found to contain $8\mathrm{.}482$mmol of the alconol and $8\mathrm{.}000$mmol of water. If the mole fraction of alcohol in the bulk solution is $0\mathrm{.}5,$ calculate ${?}_{\text{R}\text{O}\text{H}}{}^n$ and ${?}_{\text{R}\text{O}\text{H}}{}^{H2O}$ where $\text{'}n$ is the total number of moles and $$ is the surface excess.

$(4)$