JEE Main 2006 — Chemical Bonding And Molecular Structure Question with Solution

(A) Molecular orbital configuration of O $${}_2^{2-}$$ (18 electrons) is

$${\sigma }_{1s^2}{\sigma }_{1s^2}^{\ast }{\sigma }_{2s^2}{\sigma }_{2s^2}^{\ast }{\sigma }_{2p_z^2}{\pi }_{2p_x^2}={\pi }_{2p_y^2}{\pi }_{2p_x^2}^{\ast }={\pi }_{2p_y^2}^{\ast }$$

So O $${}_2^{2-}$$ has no unpaired electrons.

(B) Molecular orbital configuration of B₂ (10 electrons) is

$${\sigma }_{1s^2}{\sigma }_{1s^2}^{\ast }{\sigma }_{2s^2}{\sigma }_{2s^2}^{\ast }{\pi }_{2p_x^1}={\pi }_{2p_y^1}$$

Here in B₂, 2 unpaired electrons present.

(C) Moleculer orbital configuration of $$N_2^{+}$$ (13 electrons)

= $${\sigma }_{1s^2}{\sigma }_{1s^2}^{\ast }{\sigma }_{2s^2}{\sigma }_{2s^2}^{\ast }{\pi }_{2p_x^2}={\pi }_{2p_y^2}{\sigma }_{2p_z^1}$$

Here in $$N_2^{+}$$, 1 unpaired electron present.

(D) Molecular orbital configuration of O₂ (16 electrons) is

$${\sigma }_{1s^2}{\sigma }_{1s^2}^{\ast }$$ $${\sigma }_{2s^2}{\sigma }_{2s^2}^{\ast }$$ $${\sigma }_{2p_z^2}{\pi }_{2p_x^2}={\pi }_{2p_y^2}{\pi }_{2p_x^1}^{\ast }={\pi }_{2p_y^1}^{\ast }$$

So O$${}_2$$ has 2 unpaired electrons.