What does the pH scale measure?

The pH scale specifically measures the concentration of hydrogen ions (H+) in a solution, which indicates how acidic or basic that solution is. A lower pH value corresponds to a higher concentration of hydrogen ions, making the solution more acidic, while a higher pH value indicates a lower concentration of hydrogen ions, making the solution more basic (or alkaline). This scale typically ranges from 0 to 14, with 7 being neutral. Understanding pH is fundamental in various biological and chemical processes, as it can affect enzymatic reactions, nutrient availability, and overall organism health. Other options, while related to different aspects of water chemistry or biological activity, do not correspond to the measurement provided by the pH scale.