Assertion :-The acetylene molecule is linear in shape.
Reason :- The hybrid state of both the carbon atoms in acetylene is `sp^2`.

Options

A. If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion
B. If both Assertion and Reason are CORRECT but Reason is not the CORRECT explanation of the Assertion.
C. If Assertion is CORRECT but Reason is INCORRECT.
D. If Assertion is INCORRECT but Reason is CORRECT.

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion:**
- The assertion states that the acetylene molecule is linear in shape.
- Acetylene (C₂H₂) has a molecular structure represented as H-C≡C-H, where the two carbon atoms are connected by a triple bond.

2. **Analyzing the Structure:**
- In acetylene, each carbon atom is bonded to one hydrogen atom and to the other carbon atom through a triple bond.
- The triple bond consists of one sigma bond and two pi bonds, which restricts the rotation around the bond axis and leads to a linear arrangement of the atoms.

3. **Determining Hybridization:**
- To understand the shape, we need to look at the hybridization of the carbon atoms in acetylene.
- The ground state electron configuration of carbon is 1s² 2s² 2p².
- In the excited state, one electron from the 2s orbital is promoted to the 2p orbital, resulting in the configuration: 1s² 2s¹ 2p³.
- The two carbon atoms then undergo hybridization to form two sp hybrid orbitals (one from each carbon atom) for the formation of the triple bond and the sigma bond with hydrogen.

4. **Shape Determination:**
- The sp hybridization leads to a linear geometry because the two sp hybrid orbitals arrange themselves 180 degrees apart.
- Therefore, the assertion that acetylene is linear is correct.

5. **Analyzing the Reason:**
- The reason states that the hybrid state of both carbon atoms in acetylene is sp².
- This is incorrect because, as established, the hybridization of carbon in acetylene is sp, not sp².

6. **Conclusion:**
- The assertion is correct (acetylene is linear), but the reason provided is incorrect (the hybridization is sp, not sp²).
- Therefore, the correct answer is that the assertion is true, but the reason is false.

**Final Answer:**
- Assertion is correct, but the reason is incorrect.

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