1) Answer is: the hydrogen ion concentration is 1·10⁻¹ mol/L.
[OH⁻] = 1·10⁻¹³ mol/L, equilibrium concentration of hydroxide anion.
[H⁺] is the concentration of hydrogen ions.
[OH⁻] · [H⁺] = 10⁻¹⁴ mol²/L², ionicproduct of water on room temperature.
[H⁺] = 10⁻¹⁴ mol²/L² ÷ 1·10⁻¹³ mol/L.
[H⁺] = 10⁻¹ mol/L = 0,1 mol/L.
2) pH = -log[H⁺], approximately the negative of the base 10 logarithm of the molar concentration of hydrogen ions
pH = -log(10⁻¹ mol/L).
pH = 1.
This solution is acid, because pH value (potential of hydrogen) is less than seven. If pH is greater than seven, slotion is base and if pH is equal seven, solution is neutral.
