INDICATOR PAPER With colour scale pH6.5-9.0 packages that pH paper comes in often includes a color-coded scale indicating the pH that something has when the paper turns a certain color.
ndicators are substances that change their color when they come in contact with acids or bases. ex. litmus paper, phenolphthalein, methyl orange etc... ph scale is an universal indicator.It states it nature(acidic/basic/neutral) and also shows its strength . It is helpful in showing the properties of the substances.
A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions.