What is the [oh-] in a solution
with a poh of 7.86?
[oh-] = [? ] x

1.380 × 10^-8 M

The pH is the measure of alkalinity or acidity of a substance.

It is the negative logarithm of H+ ions concentration [H+].

pH = -log[H+]

pOH on the other hand is negative logarith of OH- concentration [OH-].

pOH = -log[OH-]

In this case;

pOH = 7.86

We can calculate the [OH-]

pOH = -log[OH-]

But, pOH = 7.86

pOH = -log[OH-]

-log[OH-] = 7.86

[OH-] = Antilog -7.86

       = 1.380 × 10^-8 M

Therefore, [OH-] is 1.380 × 10^-8 M

answer; i believe that the correct answer is (a); a large rock being weathered by wind and rain;

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.