Among the following , the most stable conformation of n-butane is

Options

A.
B.
C.
D.

Explanation

To find the most stable conformation of n-butane, we need to analyze the different conformations it can adopt: eclipsed, gauche, anti, and fully eclipsed. Here’s a step-by-step breakdown of the process:

### Step 1: Understand the Structure of n-Butane
n-Butane (C4H10) consists of a straight-chain of four carbon atoms. Each carbon is bonded to hydrogen atoms to satisfy the tetravalency of carbon.

### Step 2: Identify the Types of Conformations
There are several conformations that n-butane can adopt:
1. **Eclipsed Conformation**: The substituents (hydrogens and methyl groups) on adjacent carbons are aligned with each other, leading to maximum steric hindrance.
2. **Gauche Conformation**: The substituents are staggered but are positioned close to each other, leading to some steric hindrance.
3. **Anti Conformation**: The substituents are staggered and positioned opposite each other, minimizing steric hindrance.
4. **Fully Eclipsed Conformation**: The substituents are directly behind each other, leading to the highest steric hindrance.

### Step 3: Draw the Conformations
- **Eclipsed**: CH3 and CH3 are aligned, causing steric hindrance.
- **Gauche**: CH3 and CH3 are staggered but close to each other.
- **Anti**: CH3 groups are opposite each other, minimizing steric hindrance.
- **Fully Eclipsed**: CH3 groups are aligned, causing maximum steric hindrance.

### Step 4: Analyze Stability
- The **fully eclipsed conformation** has the highest steric hindrance due to the overlapping of groups.
- The **eclipsed conformation** has significant steric hindrance as well but is slightly better than fully eclipsed.
- The **gauche conformation** has some steric hindrance but is more stable than the eclipsed forms.
- The **anti conformation** has the least steric hindrance since the bulky groups (CH3) are positioned opposite each other.

### Conclusion
The most stable conformation of n-butane is the **anti conformation** because it minimizes steric hindrance between the bulky methyl groups.

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