A solution with a pH of 7 has a [OH1-] of

Answer 1

pH + pOH = pKw = 14. You know pKw and pH, solve for pOH.
Then pOH = -log(OH^-)
Solve for OH^-

Answer 2

7M. Is that correct?

Answer 3

no. pOH is 7 (but not molar).
pH + pOH = 14
pH = 7; therefore, pOH = 7
Now do pOH = -log(OH^-) and solve for OH^-

Answer 4

1 x 10-7 M?? Is that correct?