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# Number of paramagnetic oxides among the following given oxides is

Question:

Number of paramagnetic oxides among the following given oxides is

$\mathrm{Li}_{2} \mathrm{O}, \mathrm{CaO}, \mathrm{Na}_{2} \mathrm{O}_{2}, \mathrm{KO}_{2}, \mathrm{MgO}$ and $\mathrm{K}_{2} \mathrm{O}$

1. 1

2. 2

3. 3

4. 0

Correct Option: 1

Solution:

$\mathrm{Li}, \mathrm{O} \Rightarrow 2 \mathrm{Li}^{+} \quad \mathrm{O}^{2-}$           $\mathrm{MgO} \Rightarrow \mathrm{Mg}^{2+} \mathrm{O}^{2-}$

$\mathrm{CaO} \Rightarrow \mathrm{Ca}^{2+} \quad \mathrm{O}^{2-}$             $\mathrm{K}_{2} \mathrm{O} \Rightarrow 2 \mathrm{~K}^{+} \quad \mathrm{O}^{2-}$

$\mathrm{Na}_{2} \mathrm{O}_{2} \Rightarrow 2 \mathrm{Na}^{+} \quad \mathrm{O}_{2}^{2-}$

$\mathrm{KO}_{2} \quad \Rightarrow \mathrm{K}^{+} \quad \mathrm{O}_{2}^{-}$

$\mathrm{O}_{2}^{-} \Rightarrow$ Complete octet, diamagnetic

$\mathrm{O}^{2-} \Rightarrow \sigma_{1 \mathrm{~s}}^{2} \sigma_{1 \mathrm{~s}}^{* 2} \sigma_{2 \mathrm{~s}}^{2} \sigma_{2 \mathrm{~s}}^{* 2} \sigma_{2 \mathrm{px}}^{2} \pi_{2 \mathrm{py}}^{2} \simeq \pi_{2 \mathrm{pz}}^{2} \pi_{2 \mathrm{py}}^{* 2} \simeq \pi_{2 \mathrm{pz}}^{* 2}$ (dia)

$\mathrm{O}_{2}^{-} \Rightarrow \sigma_{1 \mathrm{~s}}^{2} \sigma_{1 \mathrm{~s}}^{* 2} \sigma_{2 \mathrm{~s}}^{2} \sigma_{2 \mathrm{~s}}^{* 2} \sigma_{2 \mathrm{px}}^{2} \pi_{2 \mathrm{py}}^{2} \simeq \pi_{2 \mathrm{pz}}^{2} \pi_{2 \mathrm{py}}^{* 2} \simeq \pi_{2 p z}^{*_{2}}$ (para)