Which of the following is paramagnetic ?

MCQ

✓

Answer

Correct option: D.

$B_2$

d
Total electron

$NO^+$ $14$

$CO$ $14$

$O_2^{2-}$ $18$

$B_2$ $10$

$N{O^ + } \Rightarrow KK.\sigma {(2s)^2}{\sigma ^*}{(2s)^2}.{(\pi 2{p_x})^2}$

$ = {(\pi 2{p_y})^2}.{(\sigma 2{p_z})^2}$ diamagnetic

$CO \Rightarrow KK.\sigma {(2s)^2}{\sigma ^*}{(2s)^2}.{(\pi 2{p_x})^2}$

$ = {(\pi 2{p_y})^2}.{(\sigma 2{p_z})^2}$ diamagnetic

$O_2^{2 - } \Rightarrow KK.\sigma {(2s)^2}{\sigma ^*}{(2s)^2}.\sigma {(2{p_z})^2}{(\pi 2{p_x})^2}$

$ = {(\pi 2{p_y})^2}.{\pi ^*}{(2{p_x})^2} = {\pi ^*}{(2{p_y})^2}$ diamagnetic

${B_2} \Rightarrow KK.\sigma {(2s)^2}{\sigma ^*}{(2s)^2}.\pi {(2{p_x})^1} = \pi {(2{p_y})^1}$ paramagnetic

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Column $I$ (Element types)	Column $II$ (Electronic configuration)
$A$. Inert-gas elements	$1.\left( {n - 1} \right){d^{1 - 10}}\,n{s^{1 - 2}}$
$B$. Transition elements	$2\,. ns^2\,np^6$
$C$. Inner-transition elements	$3.\left( {n - 2} \right){f^{1 - 14}}\,\left( {n - 1} \right){s^2}{p^6}{d^{0 - 1}}\,n{s^2}$