Assertion (A): `ClO_(2)` is a paramagnetic molecule
Reason R: Cl atom in `ClO_(2)` molecule is `sp^(3)` hybridsed

Options

A. A & are true, R is correct explanation of A
B. A & R are true, R is not correct explanation of A
C. A is true, but R is false
D. A is false, but R is true

Explanation

To solve the assertion and reason question regarding `ClO2`, we will analyze both statements step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that `ClO2` is a paramagnetic molecule.
- A molecule is considered paramagnetic if it has at least one unpaired electron.

2. **Determining the Electron Count**:
- Chlorine (Cl) has 17 electrons, and each oxygen (O) has 8 electrons (6 valence electrons).
- Therefore, the total number of electrons in `ClO2` is:
- Chlorine: 7 valence electrons
- Oxygen: 6 valence electrons × 2 = 12
- Total = 7 + 12 = 19 electrons (which is an odd number).

3. **Drawing the Lewis Structure of `ClO2`**:
- The Lewis structure can be represented as:
```
O = Cl = O
```
- In this structure, we can see that chlorine forms double bonds with both oxygen atoms.

4. **Analyzing Electron Pairing**:
- In the Lewis structure, we can pair the electrons:
- Each oxygen atom shares two electrons with chlorine (forming double bonds).
- However, chlorine has one unpaired electron in its valence shell, which confirms that `ClO2` is indeed paramagnetic.

5. **Understanding the Reason (R)**:
- The reason states that the chlorine atom in `ClO2` is `sp^3` hybridized.
- To determine the hybridization, we can use the formula:
- Hybridization = (Number of valence electrons on the central atom + Number of monovalent atoms + charge) / 2.
- For chlorine in `ClO2`:
- Valence electrons = 7
- Monovalent atoms = 0 (since there are no monovalent atoms directly bonded to Cl)
- Charge = 0
- Therefore, Hybridization = (7 + 0 + 0) / 2 = 3.5, which does not correspond to `sp^3` hybridization.

6. **Conclusion**:
- The assertion (A) is true because `ClO2` is paramagnetic due to the presence of an unpaired electron.
- The reason (R) is false because the hybridization of chlorine in `ClO2` is not `sp^3`, but rather it is better described as `sp^2` due to the presence of double bonds and one lone pair.

### Final Answer:
- Assertion (A) is true.
- Reason (R) is false.
- Therefore, the correct option is that the assertion is true, but the reason is not a valid explanation for the assertion.