In an arrangement of type ABABA .... identical atoms of first layer ( A ) and third layer ( A ) are joined by a line passing through their centers . Identify the correct statement .

Options

A. No void is found on the line
B. Only tetrahedral voids are found on the line
C. Only octahedral voids are found on the line
D. Equal number of tetrahedral and octahedral voids are found on the line

Answer

To solve the question regarding the arrangement of atoms in layers A and B, let's break it down step by step.

### Step 1: Understanding the Arrangement
The arrangement described is ABABA..., where:
- A represents identical atoms in the first and third layers.
- B represents the atoms in the second layer.

### Step 2: Identifying the Layers
In this arrangement:
- The first layer (A) consists of identical atoms.
- The second layer (B) is placed above the first layer (A).
- The third layer (A) is placed above the second layer (B).

### Step 3: Analyzing the Connection
The question states that identical atoms of the first layer (A) and the third layer (A) are joined by a line passing through their centers. This implies that we are looking at the vertical alignment of the atoms from the first layer to the third layer.

### Step 4: Understanding the Void Formation
When the second layer (B) is placed on top of the first layer (A), it creates voids. The type of voids formed depends on the arrangement of the atoms:
- The triangular voids present in the first layer become tetragonal voids when the second layer is added.

### Step 5: Identifying the Type of Void
When we consider the connection between the first layer (A) and the third layer (A), we need to determine what type of void is formed:
- The voids that are formed when the first layer (A) and the third layer (A) are aligned vertically are known as tetrahedral voids.

### Conclusion
Thus, the correct statement regarding the arrangement and the voids formed is that only tetrahedral voids are found along the line joining the centers of the A atoms in the first and third layers.

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