This depends on the indicator : Solution of red cabbage, or rose flower, strawberry, or cherry.These turn lighter(yellowish) in the presence of an acid, and more darker(violet) in the presence of a...
Red & Blue litmus paper. Actually, there are many different indicators for you to try. Examples are red cabbage juice, blueberries, strong undecaf tea, spinach, beets, and onions. For these to...