Delocalised molecular orbitals are found in

The internuclear distances in $O -O$ bonds for $O_2^+ ; O_2 , O_2^-$ and $O_2^{2-}$ respectively are

During the change of $O _{2}$ to $O _{2}^{-}$, the incoming electron goes to the orbital :

When $O _2$ is adsorbed on a metallic surface, electron transfer occurs from the metal to $O _2$. The $TRUE$ statement$(s)$ regarding this adsorption is(are)

$(A)$ $O _2$ is physisorbed

$(B)$ heat is released

$(C)$ occupancy of $\pi_{2 p }^*$ of $O _2$ is increased

$(D)$ bond length of $O _2$ is increased

The total number of anti bonding molecular orbitals, formed from $2 \mathrm{~s}$ and $2 \mathrm{p}$ atomic orbitals in a diatomic molecule is_______