What does the pH scale primarily measure?

The pH scale is a vital tool in chemistry that quantifies the acidity or basicity of a solution. It measures the hydrogen ion concentration, which determines how acidic or alkaline a substance is. The scale typically ranges from 0 to 14, with values below 7 indicating acidic solutions, a value of 7 representing neutrality, and values above 7 indicating basic (alkaline) solutions.

Understanding pH is crucial in various fields, including chemistry, biology, and environmental science, as it affects chemical reactions, biological processes, and the health of ecosystems. The other options do not relate to pH measurement; for instance, temperature relates to thermal energy, gas pressure pertains to gaseous states, and dissolved salts pertain to ionic concentration and conductivity in solutions, but none of these are measured by the pH scale. Therefore, the primary function of the pH scale is to assess the acidity or basicity of a solution.