The straight chain polymer (silicones) is formed by

Options

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

Answer

To determine how straight chain polymers (silicones) are formed, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Starting Compound**: The process begins with dimethyl dichlorosilane, which has the chemical formula CH3SiCl2. This compound contains silicon (Si) and chlorine (Cl) atoms, along with methyl (CH3) groups.

2. **Hydrolysis Reaction**: The first step is hydrolysis, where dimethyl dichlorosilane reacts with water (H2O). During this reaction, the chlorine atoms are replaced by hydroxyl (OH) groups. The reaction can be represented as:
\[ \text{CH}_3\text{SiCl}_2 + 2\text{H}_2\text{O} \rightarrow \text{CH}_3\text{Si(OH)}_2 + 2\text{HCl} \]
This results in the formation of dimethylsilane (CH3Si(OH)2) and hydrochloric acid (HCl) as a byproduct.

3. **Formation of Silanol**: The product from hydrolysis is a silanol (Si(OH)2) compound. This compound has reactive hydroxyl groups that can participate in further reactions.

4. **Condensation Polymerization**: The next step is condensation polymerization. In this process, the silanol groups react with each other, releasing water molecules and forming siloxane (Si-O-Si) linkages. The reaction can be illustrated as:
\[ \text{CH}_3\text{Si(OH)}_2 + \text{CH}_3\text{Si(OH)}_2 \rightarrow \text{(CH}_3\text{SiO)}_n + n\text{H}_2\text{O} \]
Here, multiple silanol groups react to form a long chain of siloxane, resulting in a linear polymer.

5. **Final Product**: The final product is a straight-chain silicone polymer, which is characterized by repeating units of siloxane (Si-O) and methyl groups (CH3).

### Conclusion:
The straight chain polymer (silicones) is formed by the hydrolysis of dimethyl dichlorosilane (CH3SiCl2) followed by condensation polymerization.

### Correct Answer:
The correct option is **C: Hydrolysis of CH3SiCl2 followed by the condensation polymerization**.

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