Explanation:

• Percentage of argon in air is about 0.9%.
• The permanent gases whose percentages do not change from day to day are nitrogen, oxygen and argon.
• Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%.
• Gases like carbon dioxide, nitrous oxides, methane, and ozone are trace gases that account for about a tenth of one percent of the atmosphere.