In the eclipsed conformation of ethane , the dihedral angle between the gydrogen atoms of adjacent methyl groups is

Options

A. `60^(@)`
B. `120^(@)`
C. `0^(@)`
D. `180^(@)`

Answer

To solve the question regarding the dihedral angle between hydrogen atoms of adjacent methyl groups in the eclipsed conformation of ethane, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Dihedral Angle**:
- The dihedral angle (or torsional angle) is defined as the angle between two bonds that originate from different atoms. In the context of ethane, we will consider the bonds between the hydrogen atoms attached to the adjacent carbon atoms.

2. **Visualizing Ethane**:
- Ethane (C2H6) consists of two carbon atoms, each bonded to three hydrogen atoms. When we represent ethane using a Newman projection, we can visualize how the atoms are arranged.

3. **Newman Projection**:
- In the Newman projection, one carbon atom is positioned in front of the other. For ethane, we can represent one carbon (C1) in the front and another carbon (C2) in the back. Each carbon has three hydrogen atoms.

4. **Eclipsed Conformation**:
- In the eclipsed conformation, the hydrogen atoms on the front carbon overlap with the hydrogen atoms on the back carbon. This means that the hydrogen atoms are aligned directly behind one another.

5. **Identifying the Dihedral Angle**:
- In the eclipsed conformation, the dihedral angle between the hydrogen atoms of adjacent methyl groups (the hydrogen atoms on the front carbon and the back carbon) is measured. Since these hydrogen atoms are directly aligned, the dihedral angle is 0 degrees.

6. **Conclusion**:
- Therefore, in the eclipsed conformation of ethane, the dihedral angle between the hydrogen atoms of adjacent methyl groups is **0 degrees**.