Which pH measuring tool allows for color comparison?

The pH measuring tool that allows for color comparison is litmus paper. Litmus paper is designed to change color when it comes into contact with an acidic or basic solution, providing a visual indication of the pH level. The paper is typically treated with natural dyes that react to the hydrogen ion concentration in a solution, making it easy to compare the resulting color against a standard color chart to determine whether the solution is acidic, neutral, or basic.

In contrast, a pH probe measures pH electronically and provides a numerical output rather than a color change; it is more precise and is used for a direct measurement of pH levels but lacks the visual color comparison aspect. A colorimeter is an instrument that measures the concentration of colored compounds in a solution by measuring the intensity of color, but it is not specifically designed for pH measurement alone. Similarly, a conductivity meter measures the electrical conductivity of a solution, which can provide information about ion concentration but does not involve any color comparison or direct measurement of pH. Thus, litmus paper stands out for its straightforward, visual method of assessing pH through color comparison.