4.9.1.1

4.9.1.1 The proportions of different gases in the atmosphere

Content

  • For 200 million years, the proportions of different gases in the atmosphere have been much the same as they are today:
  • about four-fifths (approximately 80%) nitrogen
  • about one-fifth (approximately 20%) oxygen
  • small proportions of various other gases, including carbon dioxide, water vapour and noble gases.

MS 1c Use ratios, fractions and percentages