Answer:
When a drop of food coloring is added to hot water, the water molecules move faster and spread apart, allowing the food coloring to mix quickly and evenly with the water. As a result, the color will spread rapidly and uniformly throughout the water.
In cold water, the water molecules move slower, and there is less space between them. This means that the food coloring takes longer to mix with the water, and may even sink to the bottom before slowly dispersing. The color will not be as uniform as it is in hot water.
When a drop of food coloring is added to tap water, it will behave similarly to cold water, although the specific behavior will depend on the temperature of the tap water. If the tap water is cold, the food coloring will take longer to mix, and the color may sink before dispersing. If the tap water is warm or hot, the food coloring will mix more quickly and evenly, and the color will spread throughout the water.