What percentage of atmospheric air constitutes oxygen?

Explanation

To determine the percentage of oxygen in atmospheric air, follow these steps:

1. **Understand the Composition of Air**: Recognize that air is a mixture of various gases. The primary components include nitrogen, oxygen, argon, carbon dioxide, and trace gases.

2. **Identify the Major Gases**: The major gases in the atmosphere are:
- Nitrogen: Approximately 78-79%
- Oxygen: Approximately 21%
- Argon: Approximately 0.93%
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