Choose Which Expression for the Equilibrium Constant for the Reaction $K_{\mathrm{a}}=\frac{\left[\mathrm{ClO}_{4}^{-}\right]\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]}{\left[\mathrm{HClO}_{4}\right]}$

Multiple Choice

Choose which expression for the equilibrium constant for the reaction of water with perchloric (HClO₄) acid is correct.

A) $K_{\mathrm{a}}=\frac{\left[\mathrm{ClO}_{4}^{-}\right]\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]}{\left[\mathrm{HClO}_{4}\right]}$
B) $K_{\mathrm{a}}=\frac{\left[\mathrm{HClO}_{4}\right]}{\left[\mathrm{ClO}_{4}^{-}\right]\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]}$
C) $K_{\mathrm{c}}=\frac{\left[\mathrm{ClO}_{4}^{-}\right]\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]}{\left[\mathrm{H}_{2} \mathrm{O}\right]}$
D) $K_{a}=\frac{\left[\mathrm{HClO}_{4}\right]\left[\mathrm{H}_{2} \mathrm{O}\right]}{\left[\mathrm{ClO}_{4}^{-}\right]\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]}$