During change of $O_2$ to $O_2^-$ ion, the electron adds on which one of the following orbitals
${\sigma ^ * }$ orbital
${\sigma}$ orbital
${\pi ^ * }$ orbital
${\pi}$ orbital
The bond order in $N_2^ + $ ion is
Two pi and half sigma bonds are present in
According to Molecular Orbital Theory,
($A$) $\mathrm{C}_2^{2-}$ is expected to be diamagnetic
($B$) $\mathrm{O}_2{ }^{2+}$ is expected to have a longer bond length than $\mathrm{O}_2$
($C$) $\mathrm{N}_2^{+}$and $\mathrm{N}_2^{-}$have the same bond order
($D$) $\mathrm{He}_2^{+}$has the same energy as two isolated He atoms
Among $\mathrm{H}_2, \mathrm{He}_2^{+}, \mathrm{Li}_2, \mathrm{Be}_2, \mathrm{~B}_2, \mathrm{C}_2, \mathrm{~N}_2, \mathrm{O}_2^{-}$, and $\mathrm{F}_2$, the number of diamagnetic species is (Atomic numbers: $\mathrm{H}=1, \mathrm{He}=2, \mathrm{Li}=3, \mathrm{Be}=4, \mathrm{~B}=5, \mathrm{C}=6, \mathrm{~N}=7, \mathrm{O}=8, \mathrm{~F}=9$ )
Among the following, the molecule expected to be stabilized by anion formation is