Not only acids but bases also change their ph value. because acids are very strong they turn red litmus to blue.
yes i agree i know base also changes their litmus colour but why do they change thier colour???
what property do they have that they are mentioned to be strong 
The Brainliest Answer!
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually. Hence, a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+) in the Arrhenius model.
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