Which of the following best describes the relationship between pH and acidity?

The relationship between pH and acidity is fundamentally based on the concentration of hydrogen ions (H⁺) in a solution. The pH scale is logarithmic and inversely related to the acidity of a solution. A lower pH value signifies a higher concentration of hydrogen ions, which means the solution is more acidic. Conversely, a higher pH value indicates a lower concentration of hydrogen ions, reflecting a more basic or alkaline solution.

Therefore, when the pH increases, the acidity decreases—meaning a higher pH corresponds to lower acidity. This understanding aligns perfectly with the concept that an increase in pH signifies a move towards a less acidic environment. The correct interpretation of the pH scale highlights how acidity and pH are interconnected, establishing that higher pH indeed indicates lower acidity.