Which of the following statements is not about the voids ?

Options

A. Octahedral void is formed at the centre of six spheres which lies at the apices of a regular octahedron
B. There is one octahedral site for each sphere
C. There are two tetrahedral sites for each sphere
D. Octahedral voids are formed when the triangular voids in second layer exactly overlap with similar voids in the first layer .

Explanation

To solve the question "Which of the following statements is not about the voids?", we need to analyze the provided statements regarding tetrahedral and octahedral voids in solid-state chemistry.

### Step-by-Step Solution:

1. **Understanding Voids**:
- Voids in a crystal lattice are empty spaces where smaller atoms can fit.
- There are two main types of voids: tetrahedral voids and octahedral voids.

2. **Tetrahedral Voids**:
- A tetrahedral void is formed when four atoms are arranged in a tetrahedral shape, where one atom is at the center and three atoms are at the corners.
- The coordination number of a tetrahedral void is 4, meaning the atom in the void touches four surrounding atoms.

3. **Octahedral Voids**:
- An octahedral void is formed when six atoms are arranged in an octahedral shape, where one atom is at the center and three atoms are at the corners of two opposite faces.
- The coordination number of an octahedral void is 6, meaning the atom in the void touches six surrounding atoms.

4. **Locating Voids**:
- Tetrahedral voids are located at positions like (A/4, A/4, A/4) in a cubic lattice, and there are 8 tetrahedral voids per unit cell.
- Octahedral voids are located at the edge centers and body center of the cubic lattice, with a total of 4 octahedral voids per unit cell.

5. **Analyzing Statements**:
- We need to evaluate the statements given in the question to identify which one is incorrect.
- The statements provided in the transcript include:
- Octahedral voids are formed at the center of 6 spheres (True).
- There is one octahedral void for each sphere (True).
- There are two tetrahedral voids for each sphere (True).
- Octahedral voids are formed when triangular voids in the second layer exactly overlap with similar voids in the first layer (False).

6. **Identifying the Incorrect Statement**:
- The last statement about octahedral voids overlapping is incorrect. Octahedral voids are formed when triangular voids do not overlap exactly.

### Conclusion:
The statement that is not true about voids is: "Octahedral voids are formed when triangular voids in the second layer exactly overlap with similar voids in the first layer."