Which of the following formulas describes nitrogen fixation?

Options

A. `N_(2)+3H_(2) to 3NH_(3)`
B. `2NH_(4)^(+)+2O_(2) +8e^(-) to N_(2)+4H_(2)O`
C. `2NH_(3) to N_(2) +3H_(2)`
D. `2N_(2) +"glucose" to 2` amino acids

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, primarily ammonia (NH₃). This process is crucial for plant nutrition as plants cannot directly utilize atmospheric nitrogen.

2. **Identifying the Chemical Reaction**:
- The chemical reaction for nitrogen fixation involves the conversion of nitrogen gas (N₂) and hydrogen gas (H₂) into ammonia (NH₃). The balanced equation for this reaction is:
\[ N_2 + 3H_2 \rightarrow 2NH_3 \]
- This equation indicates that one molecule of nitrogen gas reacts with three molecules of hydrogen gas to produce two molecules of ammonia.

3. **Evaluating the Options**:
- **Option 1**: \( N_2 + 3H_2 \rightarrow 2NH_3 \) - This is the correct representation of nitrogen fixation.
- **Option 2**: Incorrect, as it suggests nitrogen is being produced from ammonia and oxygen, which does not describe nitrogen fixation.
- **Option 3**: Incorrect, as it implies nitrogen is being released from ammonia, which is not the fixation process.
- **Option 4**: Incorrect, as it refers to amino acid formation, which is not directly related to nitrogen fixation.

4. **Conclusion**:
- The correct formula that describes nitrogen fixation is:
\[ N_2 + 3H_2 \rightarrow 2NH_3 \]