This problem is giving information about the proton concentrations of three solutions at 25 °C. Despite they are not numerically given, we can propose three scenarios to see how to approach the question.
Let the following solutions to come up:
[H⁺] = 2.63x10⁻³ M
[H⁺] = 1.00x10⁻⁷ M
[H⁺] = 4.511x10⁻⁹ M
The first step, will be the calculation of the pH for each solution via:
pH = -log([H⁺])
So that they turn out to be:
pH = -log(2.63x10⁻³ M) = 2.580
pH = -log(1.00x10⁻⁷ M) = 7.000
pH = -log(4.511x10⁻⁹ M) = 8.3457
In such a way, since acidic solutions have a pH below 7, neutral have a pH equal to 7 and basic have it above 7, we infer the first one is acidic, second one is neutral and third one is basic.
Thus, you can reproduce this methodology with the proton concentrations you are given.
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