Q:

The approximate percentages of oxygen, nitrogen, and carbon dioxide in pure air on the Earth's atmosphere are:

• 1
  0.03%, 21% and 78% respectively
• 2
  78%, 21% and 0.03% respectively
• 3
  21%, 78% and 0.03% respectively
• 4
  21%, 7.8% and 0.03% respectively