In the following questions, a statement of assertion (A) is followed by a statement of reason (R )
A : `O_(2)` is paramagnetic .
R : `N_(2)` is paramagnetic .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements , then mark (4).

Answer

To analyze the given statements, we will evaluate the assertion (A) and the reason (R) separately.

### Step 1: Evaluate the Assertion (A)
**Assertion (A): O₂ is paramagnetic.**

1. **Definition of Paramagnetism:** A substance is paramagnetic if it has unpaired electrons in its molecular orbital configuration.
2. **Molecular Orbital Configuration of O₂:**
- Oxygen (O) has 8 electrons. Therefore, O₂ has a total of 16 electrons.
- The molecular orbital configuration for O₂ is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p_z² (2 electrons in the σ2p orbital)
- π2p_x² and π2p_y² (2 electrons each in the π orbitals)
- π*2p_x¹ and π*2p_y¹ (1 electron in each of the π* orbitals)
- This results in the configuration: σ1s² σ*1s² σ2s² σ*2s² σ2p_z² π2p_x² π2p_y² π*2p_x¹ π*2p_y¹.
3. **Counting Unpaired Electrons:**
- In the configuration, there are 2 unpaired electrons (one in π*2p_x and one in π*2p_y).
4. **Conclusion:** Since O₂ has unpaired electrons, it is indeed paramagnetic.

### Step 2: Evaluate the Reason (R)
**Reason (R): N₂ is paramagnetic.**

1. **Molecular Orbital Configuration of N₂:**
- Nitrogen (N) has 7 electrons. Therefore, N₂ has a total of 14 electrons.
- The molecular orbital configuration for N₂ is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p_z² (2 electrons in the σ2p orbital)
- π2p_x² and π2p_y² (2 electrons each in the π orbitals)
- This results in the configuration: σ1s² σ*1s² σ2s² σ*2s² σ2p_z² π2p_x² π2p_y².
2. **Counting Unpaired Electrons:**
- In this configuration, all electrons are paired (2 in σ1s, 2 in σ*1s, 2 in σ2s, 2 in σ*2s, 2 in σ2p_z, 2 in π2p_x, and 2 in π2p_y).
3. **Conclusion:** Since N₂ has no unpaired electrons, it is diamagnetic, not paramagnetic.

### Final Conclusion:
- **Assertion (A)** is true: O₂ is paramagnetic.
- **Reason (R)** is false: N₂ is not paramagnetic; it is diamagnetic.

### Answer:
The correct answer is option C: The assertion is true, but the reason is false.

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