In which of the following states nitric oxide is paramagnetic.

Options

A. Solid
B. Liquid
C. Gaseous
D. It is diamagnetic in all the three states

Explanation

To determine in which state nitric oxide (NO) is paramagnetic, we need to analyze the electronic configuration and behavior of NO in different states: solid, liquid, and gas.

### Step-by-Step Solution:

1. **Understanding Nitric Oxide (NO)**:
- Nitric oxide (NO) is a diatomic molecule composed of nitrogen (N) and oxygen (O).
- The molecular formula is NO, which consists of a total of 15 electrons (7 from nitrogen and 8 from oxygen).

2. **Electronic Configuration**:
- The electronic configuration of NO can be represented as follows:
- Nitrogen (N) has 7 electrons: 1s² 2s² 2p³
- Oxygen (O) has 8 electrons: 1s² 2s² 2p⁴
- When combined, the molecular orbital theory shows that NO has an unpaired electron in its molecular orbitals.

3. **States of NO**:
- **Solid State**: In the solid state, nitric oxide tends to dimerize (combine with another NO molecule) to form N₂O₂. This dimerization leads to paired electrons, resulting in a diamagnetic state.
- **Liquid State**: Similar to the solid state, in the liquid state, NO also dimerizes, which again results in paired electrons, making it diamagnetic.
- **Gaseous State**: In the gaseous state, nitric oxide exists as individual NO molecules. In this state, there is an unpaired electron in the molecular orbital, which makes it paramagnetic.

4. **Conclusion**:
- Therefore, nitric oxide is paramagnetic only in the gaseous state. In the solid and liquid states, it is diamagnetic due to dimerization.

### Final Answer:
Nitric oxide (NO) is paramagnetic in the **gaseous state**.

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