Answer:
pH = 9.4
Step-by-step explanation:
With the given molarity of OH⁻ species we can calculate the pOH of the solution:
pOH = -log[OH⁻]
pOH = 2.6
Now we can use the pOH to calculate the pH of the solution, with the following formula:
pH = 14 - pOH
pH = 14 - 2.6
pH = 9.4
So a solution containing a OH⁻ concentration of 0.0025 M has a pH of 9.4.