Question

Choose the paramagnetic species: A. $O_{2}^{2-}$, B. $NO^{+}$, C. $O_{2}$, D. $CO^{+}$, E. NO.}

• A. A, B and C only
• B. B, C and D only
• C. C, D and E only
• D. A, B and E only

Hint:

Odd electrons = Instant Paramagnetism!

Answer 1

The Correct Option is C

Step 1: Concept Paramagnetic species possess at least one unpaired electron.

Step 2: Meaning Use molecular orbital theory or electron counting. Species with an odd number of total electrons are always paramagnetic.

Step 3: Analysis A. $O_{2}^{2-}$ (18e): Diamagnetic. B. $NO^{+}$ (14e): Diamagnetic. C. $O_{2}$ (16e): Paramagnetic (2 unpaired electrons in $\pi^{*}$). D. $CO^{+}$ (13e): Paramagnetic (odd electron). E. NO (15e): Paramagnetic (odd electron).

Step 4: Conclusion Species C, D, and E are paramagnetic. Final Answer: (C)