To get the silicone `R_(3)Si-(OSiR_(2))_(n)-SiR_(3)` having `4Si-O-Si` linkage, the unit taken is:

Options

A. `4` unit of `R_(2)SiCl_(2)` and `2` unit of `R_(3)SiCl`
B. `2` unit of `R_(2)SiCl_(2)` and `2` unit of `R_(3)SiCl`
C. `3` unit of `R_(2)SiCl_(2)` and `2` unit of `R_(3)SiCl`
D. `3` unit of `R_(2)SiCl` and `2` unit of `R_(2)SiCl_(2)`

Explanation

To solve the question regarding the silicon compound with the formula `R3Si-(OSiR2)n-SiR3` having 4 Si-O-Si linkages, we need to identify the units that contribute to this structure. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Structure
The given structure is `R3Si-(OSiR2)n-SiR3`. This indicates that we have silicon (Si) atoms connected through oxygen (O) atoms, with organic groups (R) attached to the silicon.

### Step 2: Count the Silicon Atoms
In the structure, we need to identify how many silicon (Si) atoms are present. The structure indicates:
- One Si atom at the beginning (R3Si)
- One Si atom at the end (SiR3)
- The repeating unit `OSiR2` contributes to additional Si atoms.

### Step 3: Identify the Linkages
We are specifically looking for 4 Si-O-Si linkages. Each Si-O-Si linkage corresponds to a connection between two silicon atoms through an oxygen atom.

### Step 4: Determine the Units
To achieve 4 Si-O-Si linkages, we need to analyze how many units of `OSiR2` are required. Each unit contributes one Si atom and one O atom.

- The terminal SiR3 contributes 1 Si.
- The initial SiR3 contributes another Si.
- The repeating units of `OSiR2` must provide the remaining Si atoms.

### Step 5: Calculate the Required Units
To have a total of 5 Si atoms (2 from the terminal groups and 3 from the repeating units), we can set up the following:
- 2 terminal Si atoms (1 from R3Si and 1 from SiR3)
- 3 Si atoms from 3 units of `OSiR2`

Thus, we can conclude that we need:
- 2 units of R3SiCl (for the terminal Si groups)
- 3 units of R2SiCl2 (for the repeating units)

### Final Answer
The unit taken to achieve the structure with 4 Si-O-Si linkages is:
- **2 units of R3SiCl**
- **3 units of R2SiCl2**