Which measuring tool can establish the acidity or alkalinity of a solution?

pH meters, papers, and strips are specifically designed to measure the acidity or alkalinity of a solution by determining its pH level. The pH scale ranges from 0 to 14, where values below 7 indicate acidity, a value of 7 is neutral, and values above 7 indicate alkalinity.

pH meters provide a digital readout of the pH value, offering precise measurements, while pH papers and strips change color based on the pH level of the solution they are dipped into, enabling quick qualitative assessments.

Colorimetric indicator tubes are generally used to detect specific gas concentrations rather than measuring the pH of a solution. Combustible gas indicators focus on identifying flammable gases in the environment, and toxic gas sensors are meant to detect harmful gases or vapors, but none of these options are suited for determining the acidity or alkalinity of a solution. Thus, pH meters, papers, and strips are the most appropriate tools for this specific purpose.