Normal blood $pH$ is $7\mathrm{.}40.$ A patient has blood $pH=7\mathrm{.}46.$ What is the $\frac{HC{O}_3^{-}}{H_{2}C{O}_3}$ ratio in this patient's blood?

$H_{2}C{O}_3(aq)+H_{2}O(l)=HC{O}_3-(aq)+H_3{O}^{+}(aq)$

Data:

$K_a(H_{2}C{O}_3)=4\mathrm{.}5{10}^{-7}$

$15$

$3\mathrm{.}7$

$13$

$0\mathrm{.}12$