On earth the largest reservoir of nitrogen is

Options

A. the oceans
B. granite rocks
C. the air
D. the soil

Answer

**Step-by-Step Text Solution:**

1. **Understanding Nitrogen's Importance**: Nitrogen is an essential nutrient for living organisms. It is a crucial component of various biomolecules such as nucleic acids (DNA and RNA) and proteins, which are vital for life processes.

2. **Identifying Nitrogen Sources**: The primary source of nitrogen in the environment is the atmosphere. Nitrogen gas (N₂) makes up about 78% of the Earth's atmosphere.

3. **Evaluating the Options**: The question provides four options:
- Oceans
- Gray Nitrogen (not a standard term in this context)
- The Air
- The Soil

4. **Analyzing the Largest Reservoir**: Since nitrogen gas constitutes approximately 78% of the atmosphere, it serves as the largest reservoir of nitrogen on Earth.

5. **Conclusion**: Based on the analysis, the correct answer to the question "On Earth, the largest reservoir of nitrogen is" is **the air**.

**Final Answer**: The air.

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