A forensic scientist investigated a sample of black ink from a questioned document using thin-layer chromatography (TLC).
The resulting chromatogram is shown below:
a.[1]
Explain how this chromatogram shows that the black ink is a mixture and not a pure substance.
b.[1]
Calculate the RfR_fRf value of the blue dye using the equation: Rf=distance moved by spotdistance moved by solventR_f = \frac{\text{distance moved by spot}}{\text{distance moved by solvent}}Rf=distance moved by solventdistance moved by spot
c.[1]
Identify which of the two dyes (red or blue) has the smaller RfR_fRf value.