# Which one of the following is paramagnetic? i) O3 ii) N2 iii) CO iv) O2

O2 is paramagnetic

### Explanation

It is paramagnetic because it has two unpaired electrons. The atomic orbitals of the O atoms overlap to form the σ and π orbitals of the O2 molecule as per the molecular orbital theory. Therefore, oxygen has two unpaired electrons and is paramagnetic. Paramagnetism is due to the presence of unpaired electrons in the material, so most atoms with incompletely filled atomic orbitals are paramagnetic

### Paramagnetism

An atom is considered paramagnetic if even one orbital has a net spin. Examples of paramagnets include the coordination complex myoglobin, transition metal complexes, iron oxide (FeO), and oxygen (O 2 ). Paramagnetism is due to the presence of unpaired electrons in the material, so most atoms with incompletely filled atomic orbitals are paramagnetic ,