Chemical Bonding And Molecular Structure Ques 23
23. Among the following which one is not paramagnetic? [Atomic numbers : $Be=4$, $Ne=10, As=33, Cl=17]$
[1998]
(a) $Cr^{-}$
(b) $Be^{+}$
(c) $Ne^{2+}$
(d) $As^{+}$
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Answer:
Correct Answer: 23.(a)
Solution:
(a) Paramagnetic character is based upon presence of unpaired electron
$ \begin{alignedat} & Cl^{-}=1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p_{x}^{2} 3 p_{y}^{2} 3 p_{z}^{2} \\ & Be^{+}=1 s^{2} 2 s^{2} \end{aligned} $
$ \begin{gathered} Ne^{2+}=1 s^{2} 2 s^{2} 2 p_x^{1} 2 p_y^{1} 2 p_z^{0} \ As^{+}=1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{10} 4 s^{2} 4 p^{1} 4 s^{2} 4 p_x^{1} 4 p_y^{1} 4 p_z^{1} \end{gathered} $
Hence only $Cl^{-}$ do not have unpaired electrons.
BETA
