Answer is: the hydrogen ion concentration is 10⁻¹⁰ mol/L, solution is basic.
[OH⁻] =0.00001 mol/L = 10⁻⁴ M.
[OH⁻]·[H⁺] = Kw.
0.00001 mol/L ·[H⁺] = 10⁻¹⁴ mol²/L².
[H⁺] = 10⁻¹⁴ mol²/L²÷ 10⁻⁴ mol/L.
[H⁺] = 10⁻¹⁰ mol/L.
pH = -log[H⁺].
pH = -log(10⁻¹⁰ mol/L).
pH = 10.
If pH is less than seven, solution is acidic; greater than seven, solution is basic; equal seven, solution is neutral.
