Dinitrogen and dioxygen are main constituents of air but these do not react with each other to form oxides of nitrogen because

Options

A. the reaction is endothermic and requires very high temperature
B. the reaction can be initiated only in presence of a catalyst
C. oxides of nitrogen are unstable
D. `N_(2) and O_(2)` are unreactive

Explanation

### Step-by-Step Solution:

1. **Identify the Constituents**:
- The main constituents of air are dinitrogen (N₂) and dioxygen (O₂).

2. **Understand the Nature of Bonds**:
- Dinitrogen (N₂) has a triple bond between the two nitrogen atoms, which is a very strong bond.
- Dioxygen (O₂) has a double bond between the two oxygen atoms.

3. **Reactivity Consideration**:
- Despite being abundant in the atmosphere, dinitrogen and dioxygen do not readily react to form oxides of nitrogen (NO, NO₂, etc.).

4. **Energy Requirement**:
- The reaction between dinitrogen and dioxygen is endothermic, meaning it requires energy input to proceed.
- Specifically, breaking the strong triple bond in dinitrogen requires a significant amount of energy, which is not typically available in the atmosphere.

5. **Temperature Requirement**:
- To initiate the reaction, very high temperatures are necessary to provide the energy needed to break the N≡N bond.

6. **Role of Catalysts**:
- While catalysts can facilitate reactions, the primary reason for the lack of reaction between N₂ and O₂ at normal atmospheric conditions is the high bond dissociation energy and the need for high temperatures.

7. **Conclusion**:
- The main reason dinitrogen and dioxygen do not react under normal conditions is due to the strong triple bond in dinitrogen, which requires high energy and temperature to break.

### Final Answer:
Dinitrogen and dioxygen do not react with each other to form oxides of nitrogen because the reaction is endothermic and requires very high temperatures to break the strong triple bond in dinitrogen.

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