Q.Explain paper chromatography

Imagine you have a mixture of coloured inks — say, a black pen that is actually made of blue, red, and yellow dyes mixed together. If you dip a strip of paper into water, the water creeps up the paper, and the colours separate into distinct bands. That is chromatography in action.

The core idea is simple: different substances travel at different speeds when carried by a moving fluid across a fixed material. The fixed material is the stationary phase (the paper, or a column of silica gel). The moving fluid is the mobile phase (water, or a solvent like alcohol). Each component of the mixture has its own preference — some stick more strongly to the stationary phase, others prefer to dissolve in the mobile phase and move along.

The precise statement: Chromatography is a physical separation technique in which the components of a mixture are distributed between two phases — a stationary phase (fixed in place) and a mobile phase (moving over it). The separation occurs because each component has a different equilibrium distribution between the two phases, leading to different migration rates.

Think of a race. The stationary phase is like a sticky track. The mobile phase is the wind pushing the runners. Each runner (component) has a different "stickiness" to the track and a different "willingness" to be pushed by the wind. The runner that sticks least and moves most with the wind goes farthest. The one that sticks hardest barely moves.