current atmosphere

• Why are nitrogen levels so high?

  because nitrogen is inert
• When did our current atmosphere reach it's gas levels?

  200 million years ago
• What percentage of nitrogen is in our atmosphere?

  78% or 80%
• What percentage of oxygen is in our atmosphere?

  21% or 20%
• Name 3 other gases in our atmosphere that make up less than 1%

  carbon dioxide

  water vapour

  noble gases