Chemical Bonding And Molecular Structure Ques 18
18. The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic number 16 is
[2006]
(a) 3
(b) 4
(c) 1
(d) 2
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Answer:
Correct Answer: 18.(d)
Solution:
(d) Electronic configuration of the molecule according to molecular orbital theory, is
$\sigma 1 s^2 \sigma^* 1 s^2 \sigma 2 s^2 \sigma^* 2 s^2 \sigma 2 p_z^2(\pi 2 p_x^2=\sigma 2 p_y^2)$
$ \hspace{30mm} (\pi^* 2 p_x^2=\pi 2 p_y^2) \sigma^* 2 p_z^2 \sigma 3 s^2 \sigma^* 3 s^2 \sigma 3 p_z^2 $
$(\pi 3 p_x^{2}=\pi 3 p_y^{2})(\pi^{*} 3 p_x{ }^{1}=3 p_y{ }^{1})$
Last two electrons are unpaired. So no. of unpaired electron is 2 .
BETA
