Answer:
The garden soil become more acidic.
Explanation:
The pH is defined as -log [H⁺]. An acidic solution contains an important amount of [H⁺]. When the pH increases, H⁺ decreases doing the solution more basic. In the other way, an increasing in H⁺ concentration decreases the pH doing the solution more acidic.
The pH of the garden soil of Olivia decreases after it rained. As pH decreases, [H⁺] increases become the garden soil more acidic.
