Final answer:
The poH of an 8.4 x 10^-11 M OH- solution is 10.08.
Step-by-step explanation:
The poH of an 8.4 x 10-11 M OH- solution can be found by taking the negative logarithm of the hydroxide ion concentration. Using the formula pOH = -log [OH-], we can substitute the concentration of OH- to get the value of pOH. In this case, pOH = -log (8.4 x 10-11) = 10.08.