An unknown sample is analyzed using paper chromatography using solvent X as mobile phase. One spot is observed after the paper is developed. The same unknown substance is re-analyzed using solvent Y as the mobile phase. This time, three spots are observed after the paper is visualized. Is the unknown sample a pure substance or a mixture? Explain your answer.

The substance is a mixture

Explanation:

The question lets us know that when solvent X was used as the mobile phase, we obtained only one spot. This may deceive us into thinking that the substance is pure since a pure substance has only one spot on a chromatogram.

However, the same substance yields three spots with solvent Y. This shows that the unknown sample is a mixture of substances and solvent X was unable to fully separate the mixture.

samples.

Explanation:

Sedimentary rocks