The mineral element essential for nitrogen metabolism is:

Options

A. Zn
B. `Mn^(2+)`
C. Mo
D. `Al^(3+)`

Answer

To determine the mineral element essential for nitrogen metabolism, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are zinc, manganese, molybdenum, aluminum, and amine plus 2.

2. **Understand Nitrogen Metabolism**: Nitrogen metabolism involves the processes by which plants assimilate nitrogen and convert it into usable forms. Key enzymes involved in this process include nitrogenase and nitrate reductase.

3. **Research the Role of Each Element**:
- **Zinc**: Plays a role in various enzymatic reactions but is not directly involved in nitrogen metabolism.
- **Manganese**: Important for photosynthesis and enzyme activation but not specifically for nitrogen metabolism.
- **Molybdenum**: Known to be a crucial component of enzymes involved in nitrogen metabolism, specifically nitrogenase and nitrate reductase.
- **Aluminum**: Generally toxic to plants in high concentrations and does not play a role in nitrogen metabolism.
- **Amine plus 2**: This is not a mineral element but rather a functional group and does not pertain to this context.

4. **Conclude with the Correct Answer**: Based on the research, molybdenum is essential for nitrogen metabolism as it is a component of key enzymes involved in the process.

5. **Final Answer**: The mineral element essential for nitrogen metabolism is **molybdenum**.