The early atmosphere was

Options

A. Oxidising
B. Reducing
C. Non-reactive
D. Non-reducing

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the nature of the early atmosphere of Earth. We need to determine whether it was oxidizing, reducing, non-reactive, or non-reducing.

2. **Formation of Earth**: The Earth formed approximately 4.6 billion years ago. This is important context as it sets the timeline for the development of the atmosphere.

3. **First Life on Earth**: The first life forms appeared around 3.5 billion years ago. This indicates that there was a significant period during which the atmosphere existed before life emerged.

4. **Characteristics of the Early Atmosphere**: The early atmosphere was characterized by high temperatures due to volcanic activity. The gases present included:
- Methane (CH₄)
- Hydrogen (H₂)
- Water vapor (H₂O)
- Ammonia (NH₃)
- Carbon dioxide (CO₂)

5. **Absence of Free Oxygen**: A key point is that there was no free oxygen (O₂) in the early atmosphere. This absence is critical in determining the nature of the atmosphere.

6. **Nature of the Atmosphere**: Since there was no free oxygen, the atmosphere was reducing. In a reducing atmosphere, there are more electrons available than protons, which is the opposite of an oxidizing atmosphere where free oxygen is present.

7. **Conclusion**: Based on the evidence and characteristics discussed, the correct answer to the question is that the early atmosphere was reducing.

**Final Answer**: The early atmosphere was reducing.

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