Chromatography is used to separate components of mixtures which differ in their rates of

Step 1: Analyze the question The question asks what property differs between components in a mixture that lets chromatography separate them.

Step 2: The concept In chromatography, a mixture is placed on a stationary phase (e.g., chromatography paper, silica gel, or a column). A mobile phase (solvent) then carries the mixture along. Each component:

• dissolves in the mobile phase to a different extent, and
• is held (adsorbed) by the stationary phase with different strength.

As a result, the components move (migrate) at different speeds along the stationary phase and end up in different places. This is why we measure the Rf value (distance moved by the substance ÷ distance moved by the solvent).

Step 3: Check the options

• A. Diffusion: This is the spreading of particles from high to low concentration. It happens in the process, but it is not the basis of the separation.
• B. Migration: The components travel at different rates through the stationary phase. This is the basis of the separation.
• C. Reaction: Chromatography does not rely on chemical reaction rates.
• D. Sedimentation: This is settling under gravity, used in decantation and centrifugation.
• E. Sublimation: This is a solid changing directly to gas, used for substances like iodine or ammonium chloride.

Step 4: Answer The correct option is **B.

Tip: Link chromatography with "movement": different components move at different rates (Rf values). Link sedimentation with "settling", and sublimation with "solid to gas".