Assertion (A) : `CO_2` is linear
Reason (R) : `C` is not in ` sp-` hybridised state .

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 incorrect but (R) is correct .

Explanation

To solve the assertion-reason question regarding carbon dioxide (CO₂), we will analyze both the assertion and the reason step by step.

### Step 1: Analyze the Assertion
The assertion states that CO₂ is linear.
- **Explanation**: The molecular structure of CO₂ consists of a carbon atom double bonded to two oxygen atoms (O=C=O). The arrangement of these bonds leads to a linear geometry. According to VSEPR theory, when there are two regions of electron density around the central atom (in this case, carbon), the shape will be linear.

### Step 2: Analyze the Reason
The reason states that carbon is not in an sp hybridized state.
- **Explanation**: To determine the hybridization of carbon in CO₂, we need to count the number of sigma bonds. In CO₂, there are two double bonds (C=O), and each double bond consists of one sigma bond and one pi bond. Therefore, there are a total of two sigma bonds in CO₂. The hybridization can be determined using the formula:
\[ \text{Hybridization} = \text{Number of sigma bonds} + \text{Number of lone pairs} \]
Here, carbon has 2 sigma bonds and no lone pairs, which gives us:
\[ \text{Hybridization} = 2 + 0 = 2 \quad \Rightarrow \quad \text{sp hybridization} \]
Thus, the reason that carbon is not in an sp hybridized state is incorrect.

### Step 3: Conclusion
- The assertion (A) that CO₂ is linear is **correct**.
- The reason (R) that carbon is not in an sp hybridized state is **incorrect**.

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

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