What is the ATP requirement for formation of two molecules of ammonia from `N_(2)` ?

Options

A. 18
B. 20
C. 16
D. 12

Answer

To determine the ATP requirement for the formation of two molecules of ammonia from nitrogen gas (N₂), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nitrogen Fixation**:
- Nitrogen fixation is the process through which atmospheric nitrogen (N₂) is converted into ammonia (NH₃). This process can occur biologically (through certain prokaryotes) or non-biologically.

2. **Identifying the Key Enzyme**:
- The enzyme responsible for this biological nitrogen fixation is called nitrogenase. It is found in certain prokaryotic organisms.

3. **Analyzing the Reaction**:
- The overall reaction for the biological fixation of nitrogen can be summarized as:
\[ N_2 + 8H^+ + 16 ATP \rightarrow 2 NH_3 + 16 ADP + 16 P_i \]
- This indicates that to produce 2 molecules of ammonia, 16 molecules of ATP are consumed.

4. **Calculating ATP Requirement**:
- From the reaction, we see that for the formation of 2 molecules of ammonia, 16 ATP molecules are required.
- Therefore, the ATP requirement for the formation of two molecules of ammonia from nitrogen gas is **16 ATP**.

5. **Selecting the Correct Answer**:
- Given the options (18, 20, 16, and 12), the correct answer is **16 ATP**.

### Final Answer:
The ATP requirement for the formation of two molecules of ammonia from N₂ is **16 ATP**.