Final answer:
The pH of a solution with a molar concentration of H3O+ at 1.0 x 10^-1 is 1, making the solution acidic.
Step-by-step explanation:
If the molar concentration of H3O+ is 1.0 x 10-1, we can calculate the pH using the formula pH = -log[H3O+]. Plugging in the concentration, we find:
pH = -log(1.0 x 10-1)
pH = 1
Since the pH is lower than 7, this indicates that the solution is acidic. Thus, if the molar concentration of H3O+ is 1.0 x 10-1, the pH is 1 and the solution is acidic.