Which of the following describes the purpose of pH?

The purpose of pH is to determine the concentration of hydrogen ions in a solution, which is crucial for understanding the acidity or alkalinity of that solution. pH is a logarithmic scale used to specify how acidic or basic a water-based solution is, ranging from 0 (very acidic) to 14 (very basic), with 7 being neutral. When the concentration of hydrogen ions increases, the pH decreases, indicating a more acidic environment, which can affect biological, chemical, and physical processes in that environment.

Understanding pH is essential in various fields, including agriculture, water quality assessment, and environmental science, as it influences nutrient availability, microbial activity, and overall ecosystem health. Thus, option C correctly captures the primary role of pH in measuring the concentration of hydrogen ions in a solution.