Why is nitric oxide paramagnetic in gaseous state but the solid obtained on cooling it is diamagnetic ?

Explanation

To understand why nitric oxide (NO) is paramagnetic in the gaseous state but becomes diamagnetic when it solidifies, we can break down the explanation into a few key steps:

### Step 1: Understanding the Electronic Configuration of Nitric Oxide
Nitric oxide (NO) is a diatomic molecule consisting of nitrogen (N) and oxygen (O). The electronic configuration of nitrogen is 1s² 2s² 2p³, and for oxygen, it is 1s² 2s² 2p⁴. When these atoms combine to form NO, the total number of electrons is 11 (5 from nitrogen and 6 from oxygen).

### Step 2: Identifying Unpaired Electrons in Gaseous NO
In the gaseous state, NO has an odd number of electrons (11), which means that there is one unpaired electron. This unpaired electron is responsible for the paramagnetic behavior of nitric oxide in the gaseous state. Paramagnetic substances are attracted to magnetic fields due to the presence of unpaired electrons.

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