In a good conductor, the energy levels in a valence band

Options

A. are partially filled
B. are completely filled
C. overlap with conduction band
D. both 'a' and 'c

Answer

To solve the question regarding the energy levels in the valence band of a good conductor, we will analyze the properties of conductors and their energy bands step by step.

### Step-by-Step Solution:

1. **Understanding Energy Bands**: In solid-state physics, materials have energy bands that dictate their electrical properties. The two main bands of interest are the valence band and the conduction band.

2. **Valence Band in Conductors**: The valence band is the range of energy levels that electrons occupy in a material. In good conductors (like metals), this band is typically not completely filled with electrons.

3. **Conduction Band**: The conduction band is the range of energy levels that electrons can occupy when they are free to move and contribute to electrical conduction.

4. **Overlap of Bands**: In good conductors, the valence band and conduction band often overlap. This means that electrons can easily move from the valence band to the conduction band without needing a significant amount of energy.

5. **Partially Filled Valence Band**: In good conductors, the valence band is generally partially filled. This allows some electrons to be available for conduction, which is essential for the material's ability to conduct electricity.

6. **Conclusion**: Given the properties of good conductors, we conclude that the energy levels in the valence band are both partially filled and overlap with the conduction band.

### Final Answer:
The correct response is that in a good conductor, the energy levels in the valence band are **both partially filled and overlap with the conduction band**.