If equilibrium constant for the reaction, $\left.\mathrm{XO}^{-}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(1) \rightleftharpoons \mathrm{HXO}_{(\mathrm{aq}}\right)+\mathrm{OH}^{-}(\mathrm{aq})$ is $0.36 \times 10^{-6}$ then find the value of dissociation constant $\left(\mathrm{K}_{\mathrm{a}}\right)$ for HXO ?
(a) $0.36 \times 10^{-8}$
(b) $2.8 \times 10^{-8}$
(c) $2.8 \times 10^{-10}$
(d) $0.36 \times 10^{-6}$