188.8.131.52 The proportions of different gases in the atmosphere
- 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