The reaction of `P4` with `X` leads selectively to `P_4 O_6. X` is

Options

A. `A` dry `O_2`
B. A mixture of `O_2` and `N_2`
C. Moist `O_2`
D. `O_2` in presence of aqueous `NaOH`

Explanation

To determine the identity of substance X in the reaction of \( P_4 \) with X leading to the formation of \( P_4O_6 \), we can analyze the reaction conditions and the products formed.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- The question states that \( P_4 \) reacts with X to form \( P_4O_6 \).
- \( P_4 \) is phosphorus in its molecular form, and \( P_4O_6 \) is phosphorus trioxide.

2. **Identifying the Reactants**:
- The formation of \( P_4O_6 \) typically involves the reaction of phosphorus with oxygen.
- However, to selectively form \( P_4O_6 \) and prevent further oxidation to \( P_4O_{10} \), a controlled environment is necessary.

3. **Role of Nitrogen**:
- In this reaction, nitrogen gas (\( N_2 \)) is often used to dilute the oxygen concentration.
- This prevents the complete oxidation of \( P_4 \) to \( P_4O_{10} \).

4. **Conclusion**:
- Therefore, X must be a mixture of oxygen and nitrogen.
- This mixture allows for the selective formation of \( P_4O_6 \) without allowing further oxidation to occur.

5. **Final Answer**:
- X is a mixture of oxygen and nitrogen.