At a given temperature, the intensity of the acidic or basic character of a solution is indicated by:

The intensity of the acidic or basic character of a solution is effectively indicated by pH or hydrogen ion activity. pH is a logarithmic scale that quantifies the concentration of hydrogen ions (H+) in a solution. A lower pH value indicates a higher concentration of hydrogen ions, which corresponds to a more acidic solution, while a higher pH value indicates a lower concentration of hydrogen ions, showing a more basic or alkaline solution. Therefore, pH directly reflects the acidic or basic nature of the solution, making it the most accurate measure for determining its character.

Conductivity relates to the ability of the solution to conduct electricity, which can be influenced by the presence of ions but does not specifically indicate the solution's pH. Temperature affects the solubility and reaction rates in a solution but does not provide direct information about acidity or basicity on its own. Density measures the mass per unit volume of a solution and is not a reliable indicator of its acidic or basic character.