which of the following is not true about structure of diamond and graphite?

Options

A. In diamond, each carbon is `sp^(3)` hybridised while in graphite each carbon is `sp^(2)` hybridesed.
B. In diamond, carbon atoms are closely packed in crystal lattice while grahite has layer structure
C. Diamond is a hard substance while graphite is a soft substance
D. Graphite is thermodynamically vary less stable as compared to diamond and is amorphous form of carbon.

Answer

To determine which statement is not true about the structure of diamond and graphite, we need to analyze the properties and characteristics of both forms of carbon.

### Step-by-Step Solution:

1. **Understanding the Hybridization:**
- In diamond, each carbon atom is **sp³ hybridized**. This means that each carbon forms four single covalent bonds with four other carbon atoms, creating a three-dimensional tetrahedral structure.
- In graphite, each carbon atom is **sp² hybridized**. This allows each carbon to bond with three other carbon atoms in a planar structure, forming layers. The fourth electron is free and contributes to delocalization.

**Hint:** Remember that hybridization affects the geometry and bonding properties of the carbon atoms in diamond and graphite.

2. **Analyzing Electron Delocalization:**
- In graphite, the presence of free electrons allows for **delocalization** of electrons across the layers, which contributes to its electrical conductivity.
- In diamond, there are no free electrons due to the sp³ hybridization, which means there is no delocalization. This makes diamond an electrical insulator.

**Hint:** Consider how the arrangement of electrons influences the electrical properties of materials.

3. **Stability Comparison:**
- Graphite is thermodynamically more stable than diamond at room temperature and pressure. This is due to the energy associated with the bonding in graphite, which allows for more freedom of movement and lower energy state compared to the rigid structure of diamond.

**Hint:** Think about how thermodynamic stability relates to the energy states of different forms of carbon.

4. **Identifying the False Statement:**
- Based on the above analysis, if one of the options states that diamond has free electrons or is more stable than graphite, that statement would be false. The correct answer to the question is that diamond does not have free electrons and is not more stable than graphite.

**Hint:** Look for statements that contradict the established properties of diamond and graphite.

### Conclusion:
The statement that is not true about the structure of diamond and graphite is that diamond has free electrons or that it is more stable than graphite. The correct option is option number 4.