The concentration of H3O+ in human sweat can be as low as 2.5 × 10-6. The concentration of OH- in the sweat is , and this solution is (acidic, basic, neutral).

[OH⁻] = 4.0 × 10⁻⁹ M

Acidic

Explanation:

Step 1: Given data

Step 2: Calculate the concentration of OH⁻

We will use the following expression.

[H₃O⁺].[OH⁻] = Kw = 1.0 × 10⁻¹⁴

[OH⁻] = 1.0 × 10⁻¹⁴/[H₃O⁺] = 1.0 × 10⁻¹⁴/2.5 × 10⁻⁶ = 4.0 × 10⁻⁹ M

Step 3: Calculate the pH

We will use the following expression.

pH = -log [H₃O⁺] = -log 2.5 × 10⁻⁶ = 5.6

Since the pH < 7, the solution is acidic.

i'm assuming that the correct answer is indeed the first one/ "a"..