Which of the following statements about acids is true?

Acids are defined by their ability to donate protons (H⁺ ions) in an aqueous solution, which is a fundamental property that characterizes them chemically. One of the key indicators of an acid is its pH value, which measures the concentration of hydrogen ions in a solution. A solution with a pH less than 7 indicates an acidic environment. Thus, the statement that acids have a pH less than 7 accurately describes the nature of acids and is a reliable characteristic observed in chemistry.

The other statements about acids involve common misconceptions or incorrect properties associated with them. For example, acids typically taste sour rather than bitter; they turn litmus paper red instead of blue; and in pure form, acids are not inherently conductive until they are dissolved in water, where they ionize and create a conductive solution.