Which of the following form oxychiorides as precipitate on hydrolysis ?

Options

A. `BiCl_3`
B. `SbCl_3`
C. `C Cl_4`
D. `PbCl_2`

Answer

To solve the question "Which of the following form oxychlorides as precipitate on hydrolysis?", we will analyze the given options step by step.

### Step 1: Understand the Concept of Oxychlorides
Oxychlorides are compounds that contain both oxygen and chlorine, typically formed when certain metal chlorides undergo hydrolysis in the presence of water. The general reaction can be represented as:
\[ ECl_3 + H_2O \rightarrow E(OCl) + HCl \]
where \( E \) is the element that forms the oxychloride.

### Step 2: Analyze Each Option
We have four options to consider. We will evaluate each one to determine if it forms an oxychloride upon hydrolysis.

1. **Bismuth Trichloride (BiCl3)**
- When BiCl3 undergoes hydrolysis, it reacts with water to form bismuth oxychloride (BiOCl) as a precipitate:
\[ BiCl_3 + H_2O \rightarrow BiOCl + 2HCl \]
- **Conclusion**: BiCl3 forms an oxychloride precipitate.

2. **Antimony Trichloride (SbCl3)**
- Similarly, SbCl3 reacts with water to form antimony oxychloride (SbOCl):
\[ SbCl_3 + H_2O \rightarrow SbOCl + 2HCl \]
- **Conclusion**: SbCl3 also forms an oxychloride precipitate.

3. **Carbon Tetrachloride (CCl4)**
- CCl4 does not undergo hydrolysis because carbon does not have empty orbitals to accommodate the reaction with water.
- **Conclusion**: CCl4 does not form an oxychloride precipitate.

4. **Lead(II) Chloride (PbCl2)**
- PbCl2 is primarily ionic and dissolves in water without undergoing hydrolysis to form an oxychloride.
- **Conclusion**: PbCl2 does not form an oxychloride precipitate.

### Step 3: Final Answer
Based on the analysis:
- The compounds that form oxychlorides as precipitates on hydrolysis are **Bismuth Trichloride (BiCl3)** and **Antimony Trichloride (SbCl3)**.

Thus, the correct answer is **1 and 2**.