A pH lower than 7 is acidic, while a pH higher than 7 is alkaline. In mathematical terms, pH is the negative logarithm of the molar concentration of hydrogen ions in the solution.
To calculate pH, apply the formula pOH = -log[OH-].
-log[0.1] = 1.
Next, apply the formula pH + pOH = 14.
To isolate the pH, 14 – 1 = 13.
The pH of your NaOH solution is 13.