Identify example of sorption from following.

Sorption describes the uptake of one substance by another, encompassing both adsorption and absorption. Adsorption involves accumulation on a surface, while absorption involves uniform distribution throughout a bulk material.

In the given examples: charcoal with methylene blue shows adsorption of dye molecules on the surface; chalk dipped in ink shows absorption as ink penetrates the bulk; hydrogen over platinum and oxygen over finely divided nickel both demonstrate adsorption of gases onto metal surfaces.

All processes are types of sorption.