O₂<NO<C₂<He₂⁺
NO<O₂<C₂<He₂⁺
C₂<He₂⁺<O₂<NO
He₂⁺<O₂<NO<C₂
For diatomic species the correct order in which the bond order is increasing is He₂⁺<O₂<NO<C₂.The bond order is increasing in the order 0.5<1.5<2.5<3