`Me_3SiCl` is used during polymerisation of organo silicones because

Options

A. chain length of organo silicone polymers can be controlled by adding `Me_(3)SiCl`
B. `Me_(3)SiCl` blocks the end terminal of silicone polymer
C. `Me_(3)SiCl` improves the quality and yield of the polymer
D. `Me_(3)SiCl` acts as a catalyst during polymerisation

Explanation

To solve the question regarding why Me₃SiCl is used during the polymerization of organosilicones, we can break down the reasoning step by step.

### Step-by-Step Solution:

1. **Understanding Organosilicones**:
- Organosilicones are polymers that consist of silicon (Si) and oxygen (O) atoms, often with organic groups attached. They can form long chains, which can be represented as Si-O-Si-O... with organic groups like CH₃ attached to the silicon atoms.

**Hint**: Remember that organosilicones are characterized by their silicon-oxygen backbone and organic side groups.

2. **Role of Me₃SiCl**:
- Me₃SiCl (trimethylsilyl chloride) is a compound that can be used to modify the ends of these silicon chains. When added to the polymerization process, it can help control the chain length of the resulting polymer.

**Hint**: Think about how modifying the ends of a polymer chain can affect its properties and behavior.

3. **Chain Termination**:
- The addition of Me₃SiCl can terminate the growing polymer chain. If the chain ends with an OH group, it can continue to grow. However, if it is terminated with a trimethylsilyl group (from Me₃SiCl), the chain cannot grow any further.

**Hint**: Consider how chain termination affects the overall structure and length of the polymer.

4. **Hydrolysis Reaction**:
- When Me₃SiCl is hydrolyzed, it replaces the chlorine atom with an OH group, effectively terminating the polymer chain. This reaction can be represented as:
\[ \text{Si(CH}_3\text{)}_3\text{Cl} + \text{H}_2\text{O} \rightarrow \text{Si(CH}_3\text{)}_3\text{OH} + \text{HCl} \]

**Hint**: Focus on the chemical reaction that allows for the termination of the polymer chain.

5. **Evaluating Options**:
- Based on the above understanding, we can evaluate the options given in the question:
- **A**: Chain length of organosilicon polymer is controlled by adding Me₃SiCl. (Correct)
- **B**: Me₃SiCl blocks the N terminal of silicon polymer. (Correct, as it terminates the chain)
- **C**: Me₃SiCl improves the quality and yield of the polymer. (Incorrect, it terminates the chain)
- **D**: Me₃SiCl acts as a catalyst during polymerization. (Incorrect, it does not catalyze but terminates)

**Hint**: Analyze each option in the context of the role of Me₃SiCl in polymerization.

6. **Conclusion**:
- The correct answers are options A and B, as Me₃SiCl is used to control the chain length and block the terminal ends of the silicon polymer.

### Final Answer:
Me₃SiCl is used during polymerization of organosilicones because it controls the chain length and blocks the terminal ends of the silicon polymer.