Which of the following represents isobutyl :-

Options

A. `CH_(3)-CH_(2)-CH_(2)-CH_(2)-`
B. `CH_(3)- CH_(2)-underset(|)CH-CH_(3)`
C. `CH_(3) -overset(CH_(3))overset(|)(CH)-CH_(2)-`
D. `CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|) C-`

Answer

To determine which of the given options represents isobutyl, we need to understand the structure of the isobutyl group, which is also known as 2-methylpropyl. Here’s a step-by-step breakdown of how to identify it:

### Step 1: Understand the Structure of Isobutyl
Isobutyl is derived from isobutane, which has the IUPAC name 2-methylpropane. The structure consists of a three-carbon chain (propane) with a methyl group (CH3) attached to the second carbon.

### Step 2: Draw the Structure
1. Start with a straight chain of three carbon atoms:
- C1 - C2 - C3
2. Attach a methyl group (CH3) to the second carbon (C2):
- C1 - C2 (CH3) - C3

The structure looks like this:
```
CH3
|
CH3-C-CH2
```

### Step 3: Identify the Isobutyl Group
From the structure, we can see that isobutyl can be represented as:
- CH3 - CH - CH2 - CH3
This indicates that there is a branching at the second carbon.

### Step 4: Compare with Given Options
Now, we need to compare this structure with the options provided in the question. The correct representation of isobutyl (2-methylpropyl) should match the structure we derived.

### Conclusion
The correct option that represents isobutyl is the one that corresponds to the structure CH3 - CH - CH2 - CH3.