1 - Burning Fossil Fuels - Releases carbon dioxide
2 - Deforestation - Trees take in carbon dioxide, less trees mean less carbon dioxide is taken in
3 - Livestock Farming - animals produce large amounts of methane, more animals = more methane
1 - Sulfur Dioxide - reacts with sunlight, water, oxygen and dust to form volcanic smog
2 - Carbon Dioxide - released by volcanoes
Information of evolution of atmosphere
Antarctic Ice Cores - Each year a layer of ice forms, trapping air bubbles, deeper ice = older air
Copper reacts with oxygen to make copper oxide, using up oxygen. Heating up copper and passing air over it from syringes will show how much is used up. If yu start with 100cm of air, you'll finish with 80cm3, proving that 1/5 of the air is oxygen.