Chromatography and Rf values

A paper chromatogram is shown. The distances marked were measured along the paper. What is the retardation factor, $R_F$, of compound Y? A. 0.40 B. 0.60 C. 0.70 D. 1.67

A mixture of biphenyl, $\ce{C12H10}$, and 4-phenylphenol, $\ce{C12H10O}$, was separated by thin-layer chromatography on a polar silica plate, using the non-polar solvent cyclohexane as the mobile phase. What are the position and the retardation factor…

Each beaker used as a chromatography chamber was covered with a watch glass while the solvent rose up the paper. Explain why the chamber has to be covered for the experiment to be properly designed.

Explain why the start line must be horizontal and must be above the level of the solvent when the strip is placed in the chamber.

For the orange dye, calculate the retardation factor, $R_\mathrm{F}$, obtained in each solvent system. Dye $R_\mathrm{F}$ Orange dye, system 1 (25 % ethanol) Orange dye, system 2 (75 % ethanol)

Deduce, giving a reason, which of the two dyes, orange or violet, is the more polar.

The student suspected that the ink contained more than four dyes, and that one of the spots was two dyes that had not separated. Suggest how the student could modify the chromatography experiment to test this idea.