Higher the bond order, more is the stability. The bond order of the given species can be calculated as (i) N2= Diatomic molecule Number of electrons =(7+7+1)=15e− i.e.B.O. =2.5 (ii) C2= Diatomic molecule Number of electrons =(6+6)=12e− i.e.B.O. =2.0 (iii) Ne2= Number of bonding and antibonding electrons are equal i.e. B.O. =0 ∴ Ne2 does not exist. (iv) O22−= Diatomic molecule Number of electrons =(8+8+2)e−=18e− i.e. B.O. =1.0 Hence, correct sequence of B.O. is