How many of the following reaction yield `POCl_(3)` ?
`(i) PCl_(3) + O_(2)rarr,(ii) PCl_(5) + SO_(2) rarr,(iii) PCl_(5) + CH_(3)COOH rarr,(iv)PCl_(5) + H_(3)BO_(3) rarr,(v) PCl_(3) + SO_(2)Cl_(2) rarr`

Answer

To determine how many of the given reactions yield `POCl3`, we will analyze each reaction step by step.

### Step 1: Analyze Reaction (i)
**Reaction:** \( PCl_3 + O_2 \rightarrow ? \)

- When phosphorus trichloride (\( PCl_3 \)) reacts with oxygen (\( O_2 \)), it forms phosphoryl chloride (\( POCl_3 \)).
- **Conclusion:** This reaction yields \( POCl_3 \).

### Step 2: Analyze Reaction (ii)
**Reaction:** \( PCl_5 + SO_2 \rightarrow ? \)

- When phosphorus pentachloride (\( PCl_5 \)) reacts with sulfur dioxide (\( SO_2 \)), it produces thionyl chloride (\( SOCl_2 \)) along with phosphoryl chloride (\( POCl_3 \)).
- **Conclusion:** This reaction yields \( POCl_3 \).

### Step 3: Analyze Reaction (iii)
**Reaction:** \( PCl_5 + CH_3COOH \rightarrow ? \)

- In this reaction, phosphorus pentachloride (\( PCl_5 \)) reacts with acetic acid (\( CH_3COOH \)) to produce acyl chloride (\( CH_3COCl \)) and phosphoryl chloride (\( POCl_3 \)).
- **Conclusion:** This reaction yields \( POCl_3 \).

### Step 4: Analyze Reaction (iv)
**Reaction:** \( PCl_5 + H_3BO_3 \rightarrow ? \)

- When phosphorus pentachloride (\( PCl_5 \)) reacts with boric acid (\( H_3BO_3 \)), it produces boron oxide (\( B_2O_3 \)), hydrochloric acid (\( HCl \)), and phosphoryl chloride (\( POCl_3 \)).
- **Conclusion:** This reaction yields \( POCl_3 \).

### Step 5: Analyze Reaction (v)
**Reaction:** \( PCl_3 + SO_2Cl_2 \rightarrow ? \)

- In this case, phosphorus trichloride (\( PCl_3 \)) reacts with sulfur dichloride (\( SO_2Cl_2 \)), resulting in phosphorus pentachloride (\( PCl_5 \)) and sulfur dioxide (\( SO_2 \)).
- **Conclusion:** This reaction does not yield \( POCl_3 \).

### Final Count
Now, we summarize the results:
- Reactions yielding \( POCl_3 \): (i), (ii), (iii), (iv) → 4 reactions
- Reaction not yielding \( POCl_3 \): (v)

### Answer
**Total reactions yielding \( POCl_3 \): 4**

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