What defines the concentration of an acidic solution?

The concentration of an acidic solution is defined primarily by the presence of hydrogen ions (H⁺). An acidic solution is characterized by having a higher concentration of these hydrogen ions compared to hydroxide ions (OH⁻). When an acid dissolves in water, it dissociates to produce more H⁺ ions, thereby increasing the overall concentration of hydrogen ions in the solution.

In contrast, a neutral solution has equal concentrations of hydrogen and hydroxide ions, while a basic solution would show a higher concentration of hydroxide ions, which would not fit the definition of an acidic solution. The remaining option that describes low concentration of all ions would not accurately reflect the properties of an acid, as it does not result in the characteristic behavior of increased acidity. Thus, the identification of high concentration of hydrogen ions is what distinctly defines the nature of an acidic solution.