Which of the following reacts with `PCl_(3)` to form `PCl_(5)` ?

Options

A. `O_(2)`
B. `N_(2)`
C. Surface area of container
D. `Cl_(2)`

Explanation

To determine which compound reacts with phosphorus trichloride (PCl₃) to form phosphorus pentachloride (PCl₅), we can analyze the options provided.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
Phosphorus trichloride (PCl₃) can react with chlorine gas (Cl₂) to form phosphorus pentachloride (PCl₅). The balanced reaction is:
\[ PCl_3 + Cl_2 \rightarrow PCl_5 \]

2. **Analyzing the Options**:
We need to check each option to see if it can react with PCl₃ to produce PCl₅.

- **Option 1: O₂ (Oxygen)**
When PCl₃ reacts with O₂, it does not produce PCl₅. Instead, it forms phosphorus oxychloride (POCl₃).
\[ 2PCl_3 + O_2 \rightarrow 2POCl_3 \]
Therefore, this option is incorrect.

- **Option 2: No Reaction**
If there is no reaction, then it cannot produce PCl₅. This option is also incorrect.

- **Option 3: No Reaction**
Similar to option 2, if there is no reaction, it cannot yield PCl₅. This option is incorrect as well.

- **Option 4: Cl₂ (Chlorine gas)**
As discussed earlier, chlorine gas reacts with PCl₃ to form PCl₅.
\[ PCl_3 + Cl_2 \rightarrow PCl_5 \]
This option is correct.

3. **Conclusion**:
The only compound that reacts with PCl₃ to form PCl₅ is chlorine gas (Cl₂). Therefore, the correct answer is **Option 4**.