Diamond and Graphite are

Options

A. isomers
B. isotopes
C. allotropes
D. none of the above

Answer

**Step-by-Step Solution:**

1. **Definition of Allotropes**:
- Allotropes are different forms of the same element, where the atoms are bonded together in different ways. In this case, diamond and graphite are both allotropes of carbon.

2. **Structure of Diamond**:
- Diamond has a three-dimensional crystalline structure. Each carbon atom in diamond is sp³ hybridized, meaning it forms four strong covalent bonds with four other carbon atoms, resulting in a very hard structure.

3. **Structure of Graphite**:
- Graphite has a layered structure. In graphite, each carbon atom is sp² hybridized, forming three bonds with three other carbon atoms in a plane, creating layers that can slide over one another. This structure gives graphite its characteristic softness.

4. **Physical Properties**:
- Diamond is known for its hardness and is often used in cutting tools. In contrast, graphite is soft and slippery, making it useful as a lubricant and in pencils.

5. **Electrical Conductivity**:
- Diamond is an insulator of electricity due to its strong covalent bonds that do not allow free movement of electrons. On the other hand, graphite can conduct electricity because it has delocalized electrons that can move freely between the layers.

6. **Conclusion**:
- Therefore, diamond and graphite are allotropes of carbon that exhibit different physical properties (hardness, electrical conductivity) despite having the same chemical properties.

**Final Answer**: Diamond and graphite are allotropes of carbon with different physical properties.

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