Chemistry Regents Practice Test 2025 - Free Chemistry Regents Practice Questions and Study Guide

The pH scale specifically measures the acidity or alkalinity of a solution, which is expressed on a scale typically ranging from 0 to 14. A pH value below 7 indicates an acidic solution, a value of 7 is considered neutral, and a value above 7 indicates a basic or alkaline solution. The scale is logarithmic, meaning each whole number change on the scale represents a tenfold change in hydrogen ion concentration. This characteristic makes it a vital metric in various scientific and practical applications, such as understanding biochemical reactions in living organisms, managing water quality, and conducting chemical processes.

The other options pertain to different properties: the density relates to mass per unit volume, temperature indicates thermal energy, and electrical conductivity is related to the ability of a solution to conduct electricity, which often depends on the presence of ions. None of these properties are measured by the pH scale. Thus, the correct choice highlights the pH scale's focus on acidity and alkalinity.