Final answer:
Gas chromatography separates molecules primarily on the basis of their interaction with the stationary phase. The molecules that have a stronger interaction with the stationary phase will move more slowly and take longer to pass through the column, while those with weaker interaction will move faster and elute earlier. This difference in interaction leads to the separation of the molecules based on their retention time.
Step-by-step explanation:
Gas chromatography (GC) separates molecules primarily on the basis of their interaction with the stationary phase. In GC, a mixture is injected into a column where it interacts with a stationary phase, which can be a solid or a liquid. The molecules that have a stronger interaction with the stationary phase will move more slowly and take longer to pass through the column, while those with weaker interaction will move faster and elute earlier. This difference in interaction leads to the separation of the molecules based on their retention time, which is the time it takes for a molecule to pass through the column.