Paper chromatography is one of the commonly tested techniques in the biology olympiad. Therefore, you should be familiar with the mechanism of paper chromatography.
In simple terms, chromatography involves the separation of chemical mixtures into individual components. Each chemical has a characteristic Rf value which describes the speed at which the molecule moves over the paper in comparison with the velocity of the moving solvent. It can be calculated using the formula bellow:
Rf = Distance moved by the pigment / Distance moved by the solvent
Full protocol of paper chromatography
https://www.biologyjunction.com/chromatography_plant_pigments.htm