Because tooth paste is a base because anything that turns a blue or green when mixed with red cabbage juice(indicator) is a base.
Green
blue-pinky colour.
Reversible
I've never heard of it changing color when it is cooled, but it does change color with pH, and can be used as an indicator for acids and bases.See the Web Links for more information about using cabbage color as a pH indicator.
Red cabbage juice will turn pink when an acid is added to it. Due to the acids in a carbonated drink, 7up till turn the juice a pink colour.
When adding tomato juice to cabbage juice, the cabbage juice turns redish
green
Green
Blue/green color
When sodium hydroxide is added to red cabbage juice, the cabbage juice will change color. The cabbage indicator will turn from red/pink to blue/purple because sodium hydroxide is a strong base, causing a shift in the pH of the solution. This color change is due to the anthocyanin molecules in the red cabbage juice reacting with the change in acidity.
As tea ranges from mildly to strongly acidic, the cabbage juice should turn red or pinkish.
Citric acid mixed with cabbage juice turns the solution red/pink in color. This is due to the natural pigment in red cabbage, anthocyanin, which changes color in response to changes in pH levels.
The color change, though physical by itself, is caused by a chemical change of some colored substances in cabbage.
blue-pinky colour.
Red cabbage juice is a natural pH indicator that changes color based on the acidity or alkalinity of the solution. In vinegar, which is acidic, the cabbage juice turns red or pink. In baking soda, which is alkaline, the cabbage juice turns blue or green. This color change is due to the interaction between the pigment molecules in the cabbage juice and the different pH levels of the solutions.
When you blow into a straw in red cabbage juice, the color will change to a shade of blue or green. This occurs because the carbon dioxide from your breath reacts with the anthocyanins in the red cabbage juice, which are pH indicators. The increase in acidity from the carbon dioxide leads to a shift in color.
reversable