The composition of a gas mixture like air consists of various gases in different concentrations. In the Earth's atmosphere, the primary components are:1. Nitrogen N2 - 78.08%2. Oxygen O2 - 20.95%3. Argon Ar - 0.93%4. Carbon dioxide CO2 - 0.040%5. Neon Ne - 0.0018%6. Helium He - 0.0005%7. Methane CH4 - 0.0002%8. Krypton Kr - 0.0001%9. Hydrogen H2 - 0.00005%10. Xenon Xe - 0.000009%In addition to these, there are trace amounts of other gases and variable components like water vapor, ozone, and pollutants.Gas chromatography GC is a widely used technique for separating and analyzing the components of a gas mixture. Here's how it works:1. Sample introduction: A small volume of the gas mixture is injected into the gas chromatograph. The sample is usually vaporized before entering the column.2. Carrier gas: An inert carrier gas, such as helium or nitrogen, is used to transport the sample through the column.3. Separation column: The column is packed with a stationary phase, which can be a solid or a liquid coated on a solid support. The choice of stationary phase depends on the properties of the gases to be separated. The column can be a long, coiled tube made of glass, metal, or fused silica.4. Separation mechanism: As the gas mixture moves through the column, the components interact with the stationary phase. The interaction depends on the properties of the individual gases, such as polarity, boiling point, and molecular size. Gases with stronger interactions with the stationary phase will move more slowly through the column, while those with weaker interactions will move more quickly. This results in the separation of the components based on their retention times.5. Detector: At the end of the column, a detector measures the amount of each component as it exits the column. Common detectors used in GC include flame ionization detectors FID , thermal conductivity detectors TCD , and mass spectrometers MS .6. Data analysis: The detector generates a chromatogram, which is a plot of detector response versus time. Each peak in the chromatogram corresponds to a component in the gas mixture. The retention time, peak area, and peak height can be used to identify and quantify the components.By using gas chromatography, the composition and concentration of different gases in a mixture can be separated and analyzed effectively.