Assertion (A) : Diamond is the hardest possible substance and is a network covalent solid .
Reason (R) : All the `C` atoms in diamond are `sp^2` hybridized .

Options

A. If both (A) and (R) are correct and (R) is correct explanation of (A)
B. If both (A) and (R) are correct and (R) is not correct explanation of (A)
C. If (A) is correct , but (R) is incorrect
D. If (A) is incrorect byt (R) is incroroect .

Answer

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

### Step 1: Evaluate the Assertion
The assertion states: "Diamond is the hardest possible substance and is a network covalent solid."

- **Explanation**: Diamond is indeed one of the hardest known natural substances. It is composed of carbon atoms arranged in a tetrahedral lattice structure, where each carbon atom is covalently bonded to four other carbon atoms. This extensive network of strong covalent bonds gives diamond its exceptional hardness.

### Step 2: Evaluate the Reason
The reason states: "All the carbon atoms in diamond are sp² hybridized."

- **Explanation**: This statement is incorrect. In diamond, the carbon atoms are actually sp³ hybridized. Each carbon atom forms four sigma bonds with four neighboring carbon atoms, resulting in a three-dimensional tetrahedral structure. In contrast, sp² hybridization is found in structures like graphite, where carbon atoms are arranged in planar sheets.

### Step 3: Conclusion
Based on the evaluations:
- The assertion is **correct**: Diamond is the hardest substance and is a network covalent solid.
- The reason is **incorrect**: The carbon atoms in diamond are sp³ hybridized, not sp².

Thus, the correct answer is that the assertion is true, but the reason is false.

### Final Answer
The assertion is correct, but the reason is incorrect.

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