Hello!
The basic equations to solve this is
pH = -log[H+]
pOH = -log[OH-]
pH + pOH = 14
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Find pHpH = -log(1 * 10^-1)
pH = 1
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Find pOH1 + pOH = 14
pOH = 13
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Find OH-[OH-] = 10^(-pOH)
[OH-] = 1 * 10^-13mo/L
The answer is
![[OH-] = 1 * 10^(-13) mol/L](https://img.qammunity.org/2019/formulas/chemistry/high-school/vhzvjiwcok52a4x2zndqa8ani5ij7fbjk5.png)
Hope this helps!