The Concentration of H₃O⁺ in a Solution Is 7 $\times$ 10^-4 M at 25°C

Multiple Choice

The concentration of H₃O⁺ in a solution is 7 $\times$ 10^-4 M at 25°C.What is its hydroxide-ion concentration? (K_w = 1.01 $\times$ 10^-14)

A) 7 $\times$ 10^-4 M
B) 1 $\times$ 10^-10 M
C) 2 $\times$ 10^-10 M
D) 3 $\times$ 10^-10 M
E) 1 $\times$ 10^-11 M