Consider the following geochemical analysis of a water sample from a river.

$C{a}^{+2}=41m\frac{g}{L},M{g}^{+2}=19m\frac{g}{L},N{a}^{+1}=9m\frac{g}{L},C{l}^{-1}=13m\frac{g}{L},S{O}_4^{-2}=49m\frac{g}{L},$ Alkalinity $=161m\frac{g}{L}$ as CaCO $3,$ and the water has a $pH=8\mathrm{.}6$

a$)$ Express the concentration of $C{a}^{2+}$ in $mo\frac{l}{L}C{a}^{2+}$ and in $m\frac{g}{L}$ as $CaC{O}_3.($answer $1\mathrm{.}022{10}^{-3}$ and $102\mathrm{.}2$ respectively$)$

b$)$ Determine the ionic strength of the river water. $1$

d$)$ Estimate the activities of $C{a}^{2+},S{O}_2^{-4},$ and $C{l}^{-}$in the river water using the Davies equation to calculate the activity coefficients. $($answer $\text{'}$s respectively are: $0\mathrm{.}709,0\mathrm{.}918,$ and $0\mathrm{.}709$ and the corresponding activities: $7\mathrm{.}25E-04,3\mathrm{.}36E-04,$ and $3\mathrm{.}61E-04.$ Note: the answer for part b$)$ is $6\mathrm{.}6$mmo$\frac{l}{L}$ so $6\mathrm{.}610-3mo\frac{l}{L}$ should be used in the Davies equation$)$

answers: no units but Molar based $()$

$\backslash$table$[[C{a}^{2+},7\mathrm{.}24E-04$