Which of the following sets of species have similar bond order?

The total number of molecular orbitals formed from $2s$ and $2p$ atomic orbitals of a diatomic molecule is:

In which of the following transformations,the bond order has increased and the magnetic behaviour has changed?

Select the incorrect statement.

Among $H_2, He_2^{+}, Li_2, Be_2, B_2, C_2, N_2, O_2^{-}$,and $F_2$,the number of diamagnetic species is (Atomic numbers: $H=1, He=2, Li=3, Be=4, B=5, C=6, N=7, O=8, F=9$)

When the reaction $O_2 + e^- \to O_2^-$ occurs,identify the molecular orbital into which the electron is added.