If 2s-2p are not mixing

Question

Assuming !!2s−2p!! mixing is NOT operative, the paramagnetic species among the following is

  • !!Be_2!!
  • !!B_2!!
  • !!C_2!!
  • !!N_2!!

Solution

The electronic configurations of the given molecules, assuming that !!2s−2p!! mixing is not operative and considering the !!Z-axis!! as the internuclear axis, are as follows:

!!Be_2->!! !! \sigma1s\^2 , \sigma!!*!!1s\^2!!,!!\sigma2s\^2, \sigma!!*!!2s\^2!! (diamagnetic)

!!B_2->!! !! \sigma1s\^2!!,!!\sigma!!*!!1s\^2!!,!!\sigma2s\^2 , \sigma!!*!!2s\^2,\sigma2p_z\^2!! (diamagnetic)

!!C_2-> \sigma1s\^2!!,!!\sigma!!*!!1s\^2!!,!!\sigma2s\^2, \sigma!!*!!2s\^2,\sigma2p_z\^2,{\pi2p_x^1=\pi2p_y^1}!! (paramagnetic)

!!N_2-> \sigma1s\^2 , \sigma!!*!!1s\^2 , \sigma2s\^2, \sigma!!*!!2s\^2,\sigma2p_z^2 ,{\pi2p_x^2=\pi2p_y^2}, {\pi!!*!!2p_x^0=\pi!!*!!2p_y^0},\sigma!!*!!2p_z^0 !! (diamagnetic)

Hence, the correct answer is !!C_2!!.

This is a JEE question.

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