What pH value indicates a solution is acidic?

A solution is considered acidic when its pH value is less than 7. The pH scale ranges from 0 to 14, with lower values indicating higher concentrations of hydrogen ions (H⁺), which is characteristic of acids. A pH of exactly 7 represents a neutral solution, such as pure water, where the concentrations of hydrogen ions and hydroxide ions (OH⁻) are equal. Values greater than 7 indicate a basic or alkaline solution, where the concentration of hydroxide ions exceeds that of hydrogen ions. Therefore, the correct choice emphasizes that any pH below 7 signifies acidity due to the increased presence of hydrogen ions in the solution.