The correct option is C O2−2>O−2>O+2
Molecular orbital configuration for O+2 is (σ1s)2 (σ∗1s)2 (σ2s)2 (σ∗2s)2 (σ2pz)2 (π2px)2(π2py)2 (π∗2px)1(π∗2py)0 (σ∗2pz)0
For O+2,bond order=6−12=2.5
Molecular orbital configuration for O−2 is
(σ1s)2 (σ∗1s)2 (σ2s)2 (σ∗2s)2 (σ2pz)2 (π2px)2(π2py)2 (π∗2px)2(π∗2py)1 (σ∗2pz)0
For O−2, bond order=6−32=1.5
Molecular orbital configuration for O2−2
(σ1s)2 (σ∗1s)2 (σ2s)2 (σ∗2s)2 (σ2pz)2 (π2px)2(π2py)2 (π∗2px)2(π∗2py)2 (σ∗2pz)0
For O2−2, bond order=6−42=1.0
Thus, the order of bond orders is:
O+2>O−2>O2−2
We know that, Bond order∝1bond length
So, the correct order of bond lengths will be:
O2−2>O−2>O+2