Atmospheric Chemistry

• Compare and explain the change in percentages of carbon dioxide and oxygen. [6 marks]

  Changes:

  -> carbon dioxide has decreased

  -> oxygen has increased

  Process:

  ->volcanic activity released water vapour

  ->water vapour condensed to form oceans

  ->carbon dioxide dissolved in oceans to form carbonates

  ->carbonates form sediments

  ->carbon locked up in sedimentary rocks

  ->plants and algae evolved, they absorbed carbon dioxide by photosynthesis which also released oxygen

  -> carbon locked up in fossil fuels
• Give two reasons for the increasing percentage of carbon dioxide. [2 marks]

  Use of fossil fuels

  Deforestation

  More transport

  More industry