Among the given oxides of nitrogen , `N_2O, N_2O_3, N_2O_4` and `N_2O_5`, the number of compound/(s) having N-N bond is :

Options

A. 1
B. 2
C. 3
D. 4

Explanation

To determine the number of nitrogen oxides among \( N_2O, N_2O_3, N_2O_4, \) and \( N_2O_5 \) that contain an N-N bond, we will analyze the structures of each compound step by step.

### Step 1: Analyze \( N_2O \)

1. **Structure**: The molecular structure of \( N_2O \) can be represented as \( N \equiv N - O \) (where \( N \equiv N \) represents a triple bond between the two nitrogen atoms).
2. **N-N Bond**: There is no N-N single bond present in \( N_2O \) since the bond between the nitrogen atoms is a triple bond.

### Step 2: Analyze \( N_2O_3 \)

1. **Structure**: The structure of \( N_2O_3 \) can be represented as \( N - N \) with double bonds to oxygen atoms, or as \( N = N \) with one nitrogen having a single bond to an oxygen.
2. **N-N Bond**: In this case, we can have resonance structures that show an N-N single bond. Therefore, \( N_2O_3 \) does have an N-N bond.

### Step 3: Analyze \( N_2O_4 \)

1. **Structure**: The structure of \( N_2O_4 \) can be represented as \( N = N \) with each nitrogen bonded to two oxygen atoms (one double bond and one single bond).
2. **N-N Bond**: Similar to \( N_2O_3 \), \( N_2O_4 \) can also exhibit resonance structures that include an N-N single bond. Thus, \( N_2O_4 \) contains an N-N bond.

### Step 4: Analyze \( N_2O_5 \)

1. **Structure**: The structure of \( N_2O_5 \) can be represented as \( N = N \) with each nitrogen atom bonded to multiple oxygen atoms.
2. **N-N Bond**: In \( N_2O_5 \), the nitrogen atoms are connected by a double bond, and there are no resonance structures that show an N-N single bond. Therefore, \( N_2O_5 \) does not have an N-N bond.

### Conclusion

After analyzing all four compounds, we find that:

- \( N_2O \): No N-N bond
- \( N_2O_3 \): Has N-N bond
- \( N_2O_4 \): Has N-N bond
- \( N_2O_5 \): No N-N bond

Thus, the total number of compounds having an N-N bond is **2** (from \( N_2O_3 \) and \( N_2O_4 \)).

### Final Answer: 2

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