Which polymorph of carbon act as hadest allotrope ?

Options

A. Diamond
B. Fullerence
C. Graphite
D. All of these

Answer

### Step-by-Step Solution:

1. **Understanding Allotropes of Carbon**:
- Allotropes are different physical forms in which an element can exist. For carbon, the most common allotropes include graphite, diamond, and buckminsterfullerene.

2. **Identifying the Allotropes**:
- **Graphite**: Consists of layers of carbon atoms arranged in a hexagonal lattice. It is soft and slippery due to weak van der Waals forces between the layers.
- **Diamond**: Each carbon atom is tetrahedrally bonded to four other carbon atoms, forming a rigid three-dimensional network.
- **Buckminsterfullerene**: A molecular form of carbon that resembles a soccer ball, composed of 60 carbon atoms arranged in a spherical structure.

3. **Analyzing Hardness**:
- To determine which allotrope is the hardest, we need to consider the structure and bonding of each form.
- Diamond has a strong covalent bonding structure where each carbon atom is bonded to four other carbon atoms in a tetrahedral arrangement, resulting in a very strong and rigid network.

4. **Conclusion**:
- Among the allotropes of carbon, diamond is the hardest due to its strong covalent bonds and rigid structure. Therefore, the answer to the question is **diamond**.

### Final Answer:
The hardest allotrope of carbon is **diamond**.

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