Question

A student places a drop of purple food coloring into one beaker of water at 20°C and another drop into another beaker of water at 50°C. The temperature of the food coloring is 19°C. The picture shows what he observes.


What explains what the student observes in this investigation? Select the two that apply.

Image reference
Select an answer

A.
The food coloring moves faster in hot water.


B.
The food coloring moves slower in hot water.


C.
The food coloring is denser than the cold water.


D.
The food coloring is less dense than the cold water.

Answer 1

A and C

- A: In hotter water, molecules move faster so diffusion and mixing of the dye occur more quickly.
- C: The dye drop is cooler (19°C) and therefore denser than the slightly warmer water, so the drop sinks and forms plumes as it mixes.