What does a pH scale of less than 7 indicate about a substance?

A pH scale of less than 7 indicates that a substance is acidic. The pH scale ranges from 0 to 14, where values below 7 represent acidity, a value of 7 is neutral, and values above 7 indicate alkalinity (or basicity). Acids are characterized by their ability to donate hydrogen ions (H+) in solution, which contributes to a lower pH value. For example, common acids like citric acid or acetic acid have pH values below 7, confirming their acidic nature. Understanding this relationship is fundamental in various applications, including agriculture, where soil pH can impact nutrient availability and crop health.