Thank you for reporting, we will resolve it shortly
Q.
Which of the following species is not paramagnetic ?
JEE MainJEE Main 2017Chemical Bonding and Molecular Structure
Solution:
CO has 14 electrons (even) $\therefore $ it is diamagnetic
NO has $15 e ^{-}$ (odd) $\therefore $ it is paramagnetic and has 1 unpaired electron in $\pi^{*} 2 p$ molecular orbital.
$B _{2}$ has $10 e ^{-}$ (even) but still paramagnetic and has two unpaired electrons in $\pi 2 p_{x}$ and $\pi 2 p_{y}$ (s-p mixing).
$O _{2}$ has $16 e ^{-}$ (even) but still paramagnetic and has two unpaired electrons in $\pi^{\star} 2 p_{x}$ and $\pi^{\star} 2 p_{y}$ molecular orbitals.