Which of the following molecule have least oxidation state of the nitrogen atoms ?

Options

A. `N_(2)O_(4)`
B.
C. `HN_(3)`
D. `NH_(2)-underset(O)underset(||)(C)-NH_(2)`

Explanation

To determine which molecule has the least oxidation state of nitrogen atoms, we will analyze the oxidation states of nitrogen in the given compounds step by step.

### Step 1: Analyze N2O4
1. **Identify the oxidation state of nitrogen (N)**: Let the oxidation state of nitrogen be \( X \).
2. **Set up the equation**: In N2O4, there are 2 nitrogen atoms and 4 oxygen atoms. The oxidation state of oxygen is typically \(-2\).
\[ 2X + 4(-2) = 0 \]
\[ 2X - 8 = 0 \]
\[ 2X = 8 \implies X = +4 \]
3. **Result**: The oxidation state of nitrogen in N2O4 is \( +4 \).

### Step 2: Analyze HN3
1. **Identify the oxidation state of nitrogen (N)**: Let the oxidation state of nitrogen be \( X \).
2. **Set up the equation**: In HN3, there is 1 hydrogen atom and 3 nitrogen atoms. The oxidation state of hydrogen is \( +1 \).
\[ +1 + 3X = 0 \]
\[ 3X = -1 \implies X = -\frac{1}{3} \]
3. **Result**: The oxidation state of nitrogen in HN3 is \( -\frac{1}{3} \).

### Step 3: Analyze another nitrogen compound (e.g., NH3)
1. **Identify the oxidation state of nitrogen (N)**: Let the oxidation state of nitrogen be \( X \).
2. **Set up the equation**: In NH3, there are 3 hydrogen atoms.
\[ 3(+1) + X = 0 \]
\[ 3 + X = 0 \implies X = -3 \]
3. **Result**: The oxidation state of nitrogen in NH3 is \( -3 \).

### Step 4: Analyze another nitrogen compound (e.g., N2H4)
1. **Identify the oxidation state of nitrogen (N)**: Let the oxidation state of nitrogen be \( X \).
2. **Set up the equation**: In N2H4, there are 2 nitrogen atoms and 4 hydrogen atoms.
\[ 4(+1) + 2X = 0 \]
\[ 4 + 2X = 0 \implies 2X = -4 \implies X = -2 \]
3. **Result**: The oxidation state of nitrogen in N2H4 is \( -2 \).

### Conclusion
Now we compare the oxidation states of nitrogen from the analyzed compounds:
- N2O4: \( +4 \)
- HN3: \( -\frac{1}{3} \)
- NH3: \( -3 \)
- N2H4: \( -2 \)

The least oxidation state of nitrogen is found in **NH3**, which is \( -3 \).

### Final Answer
The molecule with the least oxidation state of nitrogen atoms is **NH3**.

---