A $35\mathrm{.}0mL$ sample of ascorbic acid, HA$,$ is titrated with $20\mathrm{.}0mL$ of a $4\mathrm{.}0{10}^{-2}mo\frac{l}{L}$ sodium hydroxide solution. What is the $pH$ of the resulting solution at the equivalence point, if $K_a$ for ascorbic acid is $9\mathrm{.}1{10}^{-5}?$