A pH indicator or acid-base indicator is a compound that changes colour in solution over a narrow range of pH values. Only a small amount of indicator compound is needed to produce a visible colour change.
There is various types of indicators paper such as : Litmus Red/ Blue,Starch, Starch Iodide, Cobalt chloride, Termeric , Congo red, PH (1-14) & PH (1-11) all are available here.
