Acetic acid, $C{H}_3\frac{C}{O}OH,$ has thechemical name ethanoic acid and is the compound that gives vinegar it's taste. A chemist carries out an experiment to determine the pKa value of $C{H}_3\frac{C}{O}OH.$ The concentration of $C{H}_3\frac{C}{O}OH$ in the vinegar sample is $0\mathrm{.}870mold{m}^{-3}$ and the $pH$ of the vinegar is $2\mathrm{.}41.$

Write the expression for the acid dissociated constant, $K_a$ of $C{H}_3\frac{C}{O}OH.$

$($A$)$

$)-$

$($B$)$

$)-$

$)-$

$($D$)$

$[H{]}^2=[K_a][C{H}_3\frac{C}{O}OH]$