Which of the following is a good conductor of electricity?

Options

A. Diamond
B. Graphite
C. Coal
D. None

Explanation

To determine which of the following materials is a good conductor of electricity among diamond, graphite, coal, or none of these, we can analyze the properties of each substance:

### Step 1: Identify the materials
The materials given in the question are:
- Diamond
- Graphite
- Coal
- None of these

### Step 2: Analyze the structure of each material
1. **Diamond**:
- Diamond has a tetrahedral structure where each carbon atom is covalently bonded to four other carbon atoms.
- This strong bonding creates a rigid structure, and there are no free electrons available to conduct electricity.
- Therefore, diamond is a poor conductor of electricity.

2. **Graphite**:
- Graphite has a layered structure where each layer consists of carbon atoms bonded in a hexagonal arrangement.
- Within each layer, the carbon atoms are bonded by strong covalent bonds, but the layers are held together by weaker van der Waals forces, allowing them to slide over each other.
- Importantly, each carbon atom in graphite has one free electron that is delocalized, allowing it to conduct electricity.
- Thus, graphite is a good conductor of electricity.

3. **Coal**:
- Coal is a complex mixture of carbon and other elements, and its conductivity can vary widely depending on its composition.
- Generally, coal is not considered a good conductor of electricity compared to graphite.

### Step 3: Conclusion
Based on the analysis, the only material among the options that is a good conductor of electricity is **graphite**.

### Final Answer:
**Graphite** is a good conductor of electricity.

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