What is % of `CO_(2)` in the pure dry air ?

Explanation

To determine the percentage of CO₂ in pure dry air, we can follow these steps:

### Step 1: Understand the Composition of Air
Pure dry air is primarily composed of nitrogen (N₂) and oxygen (O₂), along with smaller amounts of other gases. The major components are:
- Nitrogen (N₂): Approximately 78%
- Oxygen (O₂): Approximately 21%
- Argon (Ar): Approximately 0.93%
- Carbon Dioxide (CO₂): Approximately 0.04%
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