A solution contains 0.1 molar hydrogen ions (H+). This means the solution is likely:
If a solution contains hydrogen ions, then it will be acidic, which means low pH. We can calculate the pH with the pH equation, where pH = -log (H+), or we can use our intuition. 0.1 molarity of ions is quite strong, and we would expect it to be a strong acid, which would mean it must be below pH 2.0.