Answer:
4.35 * 10^-8 M
Step-by-step explanation:
Since the concentration of the hydronium ion= 2.3 X 10^-7 M
And we know that;
[H3O^+] [OH^-] = 1 * 10^-14
[H3O^+] = concentration of the hydronium ion
[OH^-] = concentration of the hydroxide ion
So;
[OH^-] =1 * 10^-14/[ H3O^+]
But [H3O^+] = 2.3 X 10^-7 M
[OH^-] = 1 * 10^-14/2.3 X 10^-7
[OH^-] = 4.35 * 10^-8 M