What is the pH of a solution with [H3O+] of 9.1 x 10-2 M?

What is the pOH of a solution at 25 oC when the pH is 7.91?

Which of the following is acidic at 25 oC? Check all that apply.

pOH = 9.26

pOH = 8.88

pOH = 6.45

pH = 1.22

pH = 9.41