Chemistry - CHEMICAL BONDING Question with Solution | TestHub

O₂⁻ (17 electrons):

Configuration: $({\sigma }_{1s}{)}^2({\sigma }_{1s}^{\ast }{)}^2({\sigma }_{2s}{)}^2({\sigma }_{2s}^{\ast }{)}^2({\sigma }_{2p}{)}^2({\pi }_{2p}{)}^4({\pi }_{2p}^{\ast }{)}^3$

Paramagnetic: Yes (1 unpaired electron in ${\pi }_{2p}^{\ast }$).

HOMO: ${\pi }_{2p}^{\ast }$ (g).

LUMO: ${\sigma }_{2p}^{\ast }$ (u).

Transition: g $\to$ u. This fits the criteria.

Li₂⁺ (5 electrons):

Configuration: $({\sigma }_{1s}{)}^2({\sigma }_{1s}^{\ast }{)}^2({\sigma }_{2s}{)}^1$

Paramagnetic: Yes (1 unpaired electron in ${\sigma }_{2s}$).

HOMO: ${\sigma }_{2s}$ (g).

LUMO: ${\sigma }_{2s}^{\ast }$ (u).

Transition: g $\to$ u. This fits the criteria.

Both O₂⁻ and Li₂⁺ are paramagnetic and undergo a g $\to$ u transition.

The final answer is $\boxed{C}$