Neet Solved Paper 2013 Question 17
Question: Which of the following is paramagnetic?
Options:
A) CO
B) $ O_2^{-} $
C) $ C{N^{-}} $
D) $ N{O^{+}} $
Show Answer
Answer:
Correct Answer: B
Solution:
- Paramagnetic species contains unpaired electrons in their molecular orbital electronic configuration. Molecular orbital configuration of the given species is as $ CO(6+8=14)=\sigma 1s^{2},\overset{*}\sigma,1s^{2}, $
$ \sigma 2s^{2},\overset{*}\sigma,2s^{2},\pi {2p _x}^{2} $
$\approx \overset{*}\pi,{2p _y}^{1} $ (All the electrons are paired so it is diamagnetic.)
$ O_2^{-}(8+8+1=17) $
$ =\sigma 1s^{2},\overset{*}\sigma,1s^{2},\sigma,2s^{2}$
$,\overset{*}\sigma,s^{2}, \sigma {2p_z}^{2} \pi {2p_x}^{2}, $
$ \pi,{2p _y}^{2},\overset{*}\pi,{2p _x}^{2}$
$\approx \overset{*}\pi,{2p _y}^{1} $
It contains one unpaired electron so it is paramagnetic. $ C{N^{-}}(6+7+1=14)= $ same as CO $ N{O^{+}}(7+8-1)= $ same as CO Thus, among the given species only $ O_2^{-} $ is paramagnetic.
