According to Molecular Orbital Theory,

A

$$C_{2}^{2-}$$ is expected to be diamagnetic

B

$$O_{2}^{2+}$$ is expected to have a longer bond length than $$O_2$$

C

$$N_{2}^{+}$$ and $$N_{2}^{-}$$ have the same bond order

D

$$He_{2}^{+}$$ has the same energy as two isolated He atoms