Which of the following species is not paramagnetic?

Question

Which of the following species is not paramagnetic?, C O, O 2, B 2, N O

MARKS App · Accepted Answer

CO has no unpaired electron while other have (Apply M.O.T)

E n e r g y l e v e l F o r m \Rightarrow

CO : {like N}_{2}; σ 1 S^{2} < \overset{*}{σ} 1 S^{2} < σ 2 S^{2} < \overset{*}{π} 2 S^{2} < π 2 P_{x}^{2} = π 2 P_{y}^{2} < σ 2 P_{z}^{2} ({NO unpaired e}^{-})

O_{2} : σ 1 S^{2} < \overset{*}{σ} 1 S^{2} < σ 2 S^{2} < \overset{*}{σ} 2 S^{2} < σ 2 P_{z}^{2} < π 2 P_{x}^{2} = π 2 P_{y}^{2} < \overset{*}{π} 2 P_{x}^{1} = \overset{*}{σ} 2 P_{y}^{1} (2 - {unpaired e}^{-})

B_{2} : σ 1 S^{2} < \overset{*}{σ} 1 S^{2} < σ 2 S^{2} < \overset{*}{σ} 2 S^{2} < π 2 P_{x}^{1} = π 2 P_{y}^{1}

( 2− unpaired e − )

NO : σ 1 S^{2} < \overset{*}{σ} 1 S^{2} < σ 2 S^{2} < \overset{*}{σ} 2 S^{2} < π 2 P_{x}^{2} = π 2 P_{y}^{2} < σ 2 P_{z}^{2} < \overset{*}{π} 2 P_{y}^{1} = \overset{*}{π} 2 P_{x}^{0} ({unpaired e}^{-})

have unpaired e- so parametic