Question

The correct statement regarding the observed magnetic properties of NO, O₂, B₂ and C₂ in their ground state is:

• A. NO, B₂ and C₂ are paramagnetic
• B. B₂, O₂ and NO are paramagnetic
• C. O₂, C₂ and NO are paramagnetic
• D. O₂, B₂ and C₂ are paramagnetic

Answer 1

Answer: (B)

B₂, O₂ and NO are paramagnetic

Answer 2

Solution:

1. Molecular Orbital (MO) Analysis:

   • NO: 15 electrons → has one unpaired electron → paramagnetic.
   • O₂: 16 electrons → two unpaired electrons in π* orbitals → paramagnetic.
   • B₂: (Total of 10 electrons) → two unpaired electrons in the π orbitals → paramagnetic.
   • C₂: (Total of 12 electrons) → electrons paired (configuration: $(\pi 2p)^4$) → diamagnetic.

2. Conclusion:

   • The paramagnetic species are NO, O₂, and B₂.

Thus, the correct option is: B₂, O₂ and NO are paramagnetic.