Which of the following species is/are having '`N-N`' bond order =2?

Options

A. `N_(3)^(-)`
B. `N_(2)F_(2)`
C. `N_(2)O_(4)`
D. `N_(2)O`

Explanation

To determine which of the given species have an N-N bond order of 2, we will analyze each species one by one and calculate their bond orders.

### Step-by-Step Solution:

1. **Identify the Species**: The species given are:
- N₃⁻ (Azide ion)
- N₂F₂ (Dinitrogen difluoride)
- N₂O₄ (Dinitrogen tetroxide)
- N₂O (Dinitrogen monoxide)

2. **Calculate the Bond Order for N₃⁻**:
- The Lewis structure of N₃⁻ shows that there are two double bonds between the nitrogen atoms: N≡N-N⁻.
- The bond order (BO) is calculated using the formula:
\[ \text{Bond Order} = \frac{\text{Number of bonding electrons}}{\text{Number of bonding pairs}} \]
- In N₃⁻, there are 6 bonding electrons (3 bonds) and 3 bonding pairs.
- Therefore, the bond order is:
\[ \text{Bond Order} = \frac{6}{3} = 2 \]

3. **Calculate the Bond Order for N₂F₂**:
- The Lewis structure of N₂F₂ shows a double bond between the two nitrogen atoms: N=N, with each nitrogen also bonded to a fluorine atom.
- Here, there are 4 bonding electrons (2 bonds) between the nitrogen atoms.
- The bond order is:
\[ \text{Bond Order} = \frac{4}{2} = 2 \]

4. **Calculate the Bond Order for N₂O₄**:
- The Lewis structure of N₂O₄ shows a single bond between the nitrogen atoms: N-N, with each nitrogen also bonded to an oxygen atom.
- There are 2 bonding electrons (1 bond) between the nitrogen atoms.
- The bond order is:
\[ \text{Bond Order} = \frac{2}{2} = 1 \]

5. **Calculate the Bond Order for N₂O**:
- The Lewis structure of N₂O shows a triple bond between the nitrogen atoms: N≡N, with one nitrogen also bonded to an oxygen atom.
- There are 6 bonding electrons (3 bonds) between the nitrogen atoms.
- The bond order is:
\[ \text{Bond Order} = \frac{6}{2} = 3 \]

6. **Conclusion**:
- From the calculations, we find:
- N₃⁻ has a bond order of 2.
- N₂F₂ has a bond order of 2.
- N₂O₄ has a bond order of 1.
- N₂O has a bond order of 3.
- Therefore, the species that have an N-N bond order of 2 are **N₃⁻ and N₂F₂**.

### Final Answer:
The species with an N-N bond order of 2 are **N₃⁻ and N₂F₂**.