The straight chain polymer is formed by

Options

A. hydrolysis of `(CH_(3))_(3) SiCl` followed by condensation polymerisation
B. hydrolysis of `(CH_(3))_(4)` Si by addition polymerisation
C. hydrolysis of `(CH_(3))_(4) SiCl_(2)` by addition polymerisation
D. hydrolysis of `(CH_(3))_(2) SiCl_(2)` following by condensation polymerisation.

Explanation

To determine which hydrolysis leads to the formation of a straight chain polymer, we will analyze the compounds provided in the question and their reactions.

### Step-by-Step Solution:

1. **Identify the Compounds**: The question provides four compounds:
- Trimethylchlorosilane
- Tetramethylsilane
- Tetramethyldichloridosilane
- Dimethyl dichloridosilane

2. **Understand Hydrolysis**: Hydrolysis involves the reaction of a compound with water, leading to the replacement of certain groups (like Cl) with hydroxyl groups (OH). This is crucial for forming silanols, which can further undergo polymerization.

3. **Analyze Dimethyl Dichlorosilane**:
- The structure of dimethyl dichlorosilane (Si(CH3)2Cl2) shows that silicon is bonded to two methyl groups and two chlorine atoms.
- Upon hydrolysis, the chlorine atoms will be replaced by hydroxyl groups:
\[ \text{Si(CH}_3\text{)}_2\text{Cl}_2 + 2 \text{H}_2\text{O} \rightarrow \text{Si(CH}_3\text{)}_2\text{(OH)}_2 + 2 \text{HCl} \]
- The product formed is dimethylsilanol (Si(CH3)2(OH)2).

4. **Condensation Polymerization**:
- The dimethylsilanol can undergo condensation polymerization where two molecules of dimethylsilanol react, leading to the removal of water and the formation of a siloxane bond (Si-O-Si):
\[ 2 \text{Si(CH}_3\text{)}_2\text{(OH)} \rightarrow \text{Si(CH}_3\text{)}_2\text{O-Si(CH}_3\text{)}_2 + \text{H}_2\text{O} \]
- This process can repeat, forming a long straight chain polymer.

5. **Conclusion**: The hydrolysis of dimethyl dichlorosilane followed by condensation polymerization results in the formation of a straight chain polymer.

### Final Answer:
The straight chain polymer is formed by the hydrolysis of dimethyl dichlorosilane followed by condensation polymerization.

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