The correct options are
A O2+2
B N2
D C2−2
Bond order for O2+2 is:
(16−2=14)O2+2=σ1s2 σ∗1s2 σ2s2 σ∗2s2 σ2P2z π2P2x=π2P2y
Bond order =10−42=62=3
Bond order for N2 is
(7+7)N2=14
σ1s2 σ∗1s2 σ2s2 σ∗2s2 π2P2x=π2P2y σ2P2z
Bond order =Nb−Na2
=10−42=62=3
Bond order for C2+2 is:
(6+6−2)C2+2=10 σ1s2 σ∗1s2 σ2s2 σ∗2s2 π2P1x=π2P1y
Bond order =Nb−Na2
=6−42=22=1
Bond order for C2−2 is:
(6+6+2)C2−2=14
σ1s2 σ∗1s2 σ2s2 σ∗2s2 π2P2x=π2P2y σ2P2z
Bond order =Nb−Na2
=10−42=3
Hence option A, B and D are correct.