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EEJ MAIN Chemistry QUESTION #5549
Question 1
Among the following species, which one is NOT paramagnetic?
  • CO✔️
  • $O_2$
  • $B_2$
  • NO
Correct Answer Explanation
CO: Total 14 electrons, MO config same as $N_2$, all electrons paired → diamagnetic (NOT paramagnetic). $O_2$: 2 unpaired $\pi^*$ electrons → paramagnetic. $B_2$: 2 unpaired $\pi$ electrons → paramagnetic. NO: 1 unpaired $\pi^*$ electron → paramagnetic. CO is the only diamagnetic species.