Question

) Using paper chromatography, the RF value for xanthophyll was 0.3 and the value for chlorophyll was 0.7. What is true for these two pigments?

A) Chlorophyll traveled farther up the paper than xanthophyll.

B) Xanthophyll is more soluble than chlorophyll a

C) Chlorophyll is a larger molecule than xanthophyll. D) Chlorophyll is more polar than xanthophyll.

Answer 1

As RF value is = distance traveleld by solute / distance traveled by solvent

So higher the RF value, more the distance traveled by the solute.

So xanthophil has lower RF value than chlorphil so we can say that chlorphil has travelled farther up the paper than xenthophil

so option A is correct

For option B:

If xanthophil is more soluble than chlorphil in the mobile phase, it would have travelled farhter up than the chlorophil as xanthophil would not be retained a much on the stationary phase if it would have more soubility in the mobile phase but it is not the case as RF value of xanthophil is lower than chlorophil.

For opiton c:

Molecular size don't impact on the RF value as the solubility or the contact of the stationary phase with solute plays a role in the paper chromatogrphy

For opiton D:

If chlorphil is more polar than xanthophil, it would have more attraction to paper as it contains lots of polar groups like OH and mobile phase is non polar so chlrophil should be non polar as RF value is high so they don't have affinity to paper which is the polar one.

So correct answer is option A: Chlorophyll traveled farther up the paper than xanthophyll.