Which of the following statement(s) is/are true?

Options

A. The lattice structure of diamond and graphite are different
B. Graphite is an impure form of carbon while diamond is a pure form
C. Graphite is harder than diamond
D. graphite is thermally more stable than diamond

Answer

To determine which statements regarding diamond and graphite are true, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement 1: The lattice structure of diamond and graphite are different.**
- In diamond, each carbon atom is sp³ hybridized and forms four strong covalent bonds with four other carbon atoms, creating a tetrahedral structure.
- In graphite, each carbon atom is sp² hybridized and forms three bonds with three other carbon atoms, resulting in a planar hexagonal structure with weaker van der Waals forces between layers.
- **Conclusion**: This statement is **true**.

2. **Statement 2: Graphite is an impure form of carbon while diamond is a pure form.**
- Both diamond and graphite are allotropes of carbon, meaning they are both pure forms of carbon but have different structural arrangements.
- **Conclusion**: This statement is **false**.

3. **Statement 3: Graphite is harder than diamond.**
- Diamond is known as the hardest natural material, while graphite is relatively soft and can be easily scratched.
- **Conclusion**: This statement is **false**.

4. **Statement 4: Graphite is thermally more stable than diamond.**
- Graphite is thermally more stable than diamond at high temperatures. Although diamond has stronger bonds, it can convert to graphite under certain conditions, indicating that graphite is more stable thermally.
- **Conclusion**: This statement is **true**.

### Final Answer:
The true statements are **1 and 4**.