Answer:
relative pH
Step-by-step explanation:
Litmus paper can be used to determine the relative pH of a substance.
Litmus paper can be used to determine if a substance is acidic, basic, or neutral. Red litmus paper will remain red if it contacts an acidic liquid, but it will turn blue if it contacts a basic liquid. Blue litmus paper will remain blue if it contacts a basic liquid, but it will turn red if it contacts an acidic liquid. Both types of litmus paper will turn purple when contacting a neutral liquid.