According to molecular orbital theory, atomic orbitals of nearly same energy of different atoms are combined and form molecule. In homodiatomic molecule two atomic orbitals which have wave function psi_(A) and psi_(B) are combined in two ways (psi_(A)pm psi_(B)) . They have two type of electron density, one is bonding [(psi_(A) pm psi_(B))^(2)] where e- density increase between nucleus. Another is antibonding [(psi_(A)pm psi_(B))^(2)] where e^(-) density decreases between nucleus. These molecular orbitals are filled according to Hund, Pauli, afbau principle. Existence of molecule depends on bond order. where bond order = ("Number of bonding "e^(-)"s- number of antibonding "e^(-)s)/(2) lf the molecule have unpaired electron it is paramagnetic otherwise diamagnetic Statement- 1: Removal of two e^(-) from N^(2), magnetic behaviour does not change while addition of two electrons in O_(2) magnetic behaviour changes. Which of the following correct trends of bond energy is possible to explain by following statement. "Successive filling of antibonding orbital reduce the bond energy between two atoms"? (I ) N_(2) gtgt O_(2) gtgtF_(2)(II) O_(2)^(+) gt O_(2) gt O_(2)^(-) (III) C_(2)^(2) gt C_(2) (IV) CI_(2) gt Br_(2) gt F_(2)