Final answer:
The concentration of argon in the atmosphere is approximately 0.001819%.
Step-by-step explanation:
The mole fraction of argon in dry air near sea level is 1.819 × 10⁻⁵. To find the concentration of argon in the atmosphere, we can convert the mole fraction to a percentage. Multiply the mole fraction by 100 to get the percentage:
Mole fraction of argon = 1.819 × 10⁻⁵
Percentage of argon = (1.819 × 10⁻⁵) × 100 = 0.001819%
Therefore, the concentration of argon in the atmosphere is approximately 0.001819%.