Which chromatography system uses silica gel stationary phase on a piece of glass and a moving phase of liquid?

• A. Thin-layer
• B. Ion-exchange
• C. Gas-liquid
• D. Partition

Answer: (A)

Thin-layer chromatography uses a thin layer of solid stationary phase, typically silica gel, coated on a flat support such as a glass plate. A liquid solvent acts as the moving phase and travels up the plate by capillary action, carrying the sample components with it. This exact description—silica gel on glass with a liquid moving phase—fits TLC. The other methods involve different setups: ion-exchange uses a resin in a column and ionic interactions; gas-liquid chromatography uses a gas as the mobile phase with a liquid stationary phase inside a column; partition chromatography describes distribution between phases but is usually discussed in column formats, not a thin glass plate. Therefore, the described system is thin-layer chromatography.