Jim, Jill, Robert, and Kim each run paper chromatography on an unknown aqueous mixture. Jim gets a red band and a blue band, Jill gets a yellow band and a blue band, Robert gets a green band, and Kim gets a red band and a yellow band.

Which student did not have more than one substance dissolved in the water?

Robert

Kim

Jill

Jim

Robert

Explanation:

Paper chromatography is an analytical technique which is used to separate different components dissolved in a mixture depending on the time taken by each component to travel up the paper. The difference in time depends on the relative affinity of a particular component towards the paper (which acts as the stationary phase) and the solution carrying the mixture (which acts as the mobile phase).

This method is commonly used to separate colored systems like a dye mixture. The presence of more than one dye in a mixture shows up as a band of a color characteristic of that component.

Jim, Jill and Kim each have two bands in their paper chromatogram which suggests that they have two substances in their mixture. However, Robert has a single green band which indicates the presence of only one substance dissolved in water.