What is paper indicator?

Answer 1

paper thet measures pH is the measure of the acidity or alkalinity of a solution. It is formally a measure of the activity of dissolved hydrogen ions (H+), but for very dilute solutions, the molarity (molar concentration) of H+ may be used as a substitute with little loss of accuracy.[1] In solution, hydrogen ions occur as a number of cations including hydronium ions (H3O+).[ Hydrion is a trademarked name for a popular line of compound pH indicators, marketed by Micro Essential Laboratory, Inc. exhibiting a series of color changes (typically producing a recognizably different color for each pH unit) over a range of pH values. Although solutions are available, the most common forms of Hydrion are a series of papers impregnated with various mixtures of indicator dyes. It is considered a "universal indicator".