The correct option is C O+2
According to MOT, bond order is given by:
B.O.=12(NB−NA) where NA and NBare the number of electrons in antibonding and bonding molecular orbital respectively,
O2⇒σ(1s)2σ∗(1s)2σ(2s)2σ∗(2s)2σ(2pz)2π(2px)2π(2py)2π∗(2px)1π∗(2py)1
Bond order for O2 = 12(10−6) = 2
Bond order for O+2 = 12(10−5) = 2.5
Bond order for O−2 = 12(10−7) = 1.5
Bond order for O2−2=12(10−8) = 1