Assertion:A tetrahedral void is surrounded by four spheres and an octahedral void is surrounded by six spheres.
Reason:The number of tetrahedral voids is double the number of close packed spheres and number of octahedral voids is equal to number of close packed spheres.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false

Explanation

To solve the question, we need to analyze the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that a tetrahedral void is surrounded by four spheres and an octahedral void is surrounded by six spheres.

**Explanation**:
- A tetrahedral void is formed when one sphere is placed in a depression created by three other spheres. This arrangement results in a tetrahedral geometry, where the coordination number is 4.
- An octahedral void is formed when six spheres are arranged in such a way that they create a central space, resembling an octahedron. This arrangement results in a coordination number of 6.

### Step 2: Understand the Reason
The reason states that the number of tetrahedral voids is double the number of close-packed spheres, and the number of octahedral voids is equal to the number of close-packed spheres.

**Explanation**:
- In a close-packed structure, for every 'n' atoms (spheres), there are 2n tetrahedral voids. This is because each atom contributes to creating two tetrahedral voids.
- For octahedral voids, there is one octahedral void for each atom in the close-packed structure, hence the number of octahedral voids is equal to 'n'.

### Step 3: Evaluate the Assertion and Reason
- Both the assertion and the reason are correct statements based on the principles of solid-state chemistry.
- However, the reason provided does not directly explain the assertion. The assertion is about the coordination of voids, while the reason discusses the quantity of voids in relation to the number of spheres.

### Conclusion
- The assertion is true, and the reason is also true, but the reason does not explain the assertion. Therefore, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

### Final Answer
Both the assertion and reason are true, but the reason is not the correct explanation of the assertion.

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