Which of the following contains a $(2C - 1e^-)$ bond?

If an extra electron is added to the hypothetical molecule $C_{2}$,this extra electron will occupy the molecular orbital.

From elementary molecular orbital theory,the electronic configuration of the singly positive nitrogen molecular ion $N_2^+$ is:

Sum of bond order of $CO$ and $NO^{+}$ is $ . . . . . . $.

Which of the following statements are correct for the peroxide ion $(O_{2}^{2-})$?
$(i)$ It has a bond order of $1$.
$(ii)$ It is diamagnetic.
$(iii)$ It has four completely filled antibonding molecular orbitals.
$(iv)$ It is isoelectronic with neon.

Stability of the species $Li_2$,$Li_2^-$ and $Li_2^+$ increases in the order of $:-$