An element playing important role in nitrogen fixation is

Options

A. Zinc
B. Molybdenum
C. Copper
D. Manganese

Answer

### Step-by-Step Solution:

1. **Understanding Nitrogen Fixation**:
- Nitrogen fixation is the process by which atmospheric nitrogen (N₂) is converted into a form that plants can use, such as ammonia (NH₃). This process is crucial for the growth of plants as nitrogen is an essential nutrient.

2. **Identifying the Elements**:
- The question provides four options: Zinc, Molybdenum, Copper, and Manganese. We need to determine which of these elements plays an important role in nitrogen fixation.

3. **Role of Molybdenum**:
- Molybdenum is identified as a micronutrient that is essential for nitrogen fixation. It acts as an activator for the enzyme nitrate reductase, which is involved in the metabolism of nitrates in plants. This indicates that molybdenum is crucial for the conversion of nitrates into forms that can be utilized by plants.

4. **Examining Other Options**:
- **Zinc**: While zinc is important for various enzymatic functions and growth, it is not directly involved in nitrogen fixation.
- **Copper**: Copper is essential for certain metabolic processes but does not play a direct role in nitrogen fixation.
- **Manganese**: Manganese is involved in various enzymatic reactions but is not specifically linked to nitrogen fixation.

5. **Conclusion**:
- Based on the analysis, the element that plays an important role in nitrogen fixation is **Molybdenum**.

### Final Answer:
**Molybdenum**

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