Acids - a substance that measures 0 to 7 in the pH scale. Turns litmus paper from blue to red.
Bases - a substance that measures 8 to 14 in the pH scale. Turns litmus paper form red to blue. A base that dissolves in water is an alkali.
Neutral - a substance that measures 7 on the pH scale. This is neither an acid or a base.
Indicator - a compound, that shows with a change of colour, if a substance is acidic or basic
No colour change indicate that it is neutral, not an acid or base
Comes in paper form, pH paper, and liquid form, universal indicator
