Question

Which of the following diatomic molecular species
has only a bonds according to Molecular Orbital
Theory?
(1)C2
(2)Be2
(3)02
(4)N2
​

Answer 1

$C_2$ diatomic molecular species has only molecular theory bonds.

Explanation:

In this question, throughout the MO configuration the $C_2$ electron configuration  are

$\sigma 1S^2 , \sigma * 1S^2, \sigma 2S^2, \sigma * 2S^2, \pi 2 p^2 x=\pi 2p^2 y$, and the  $C_2$  is the molecule, which contains only $\pi$ bonds according to MOT, that's why the $C_2$ is the correct choice.

Please find the graph image in the attachment.