What is the source of radioactive `CO_(2)` in the atmosphere?

Explanation

To understand the source of radioactive carbon dioxide (CO₂) in the atmosphere, we can break down the process into several steps:

### Step-by-Step Solution:

1. **Understanding Radioactive Carbon**:
- Radioactive carbon dioxide contains carbon-14 (C-14), which is a radioactive isotope of carbon.

2. **Formation of Carbon-14**:
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