How many ions of the following have a bond order of $2.5 ?$
$N_2^{-} ; NO^{-} ; C_2^{-} ; N_2^{+} ; C_2^{2-} ; CN^{+}$

The number of electrons present in bonding and antibonding orbitals in $O_2^{2-}$ is respectively

Fill in the blanks given below:
$(i)$ The Molecular Orbital Theory was proposed by .......... and .......... scientists.
$(ii)$ The addition of atomic orbitals results in the formation of ............ orbitals.
$(iii)$ The distribution of electrons in molecular orbitals is called .......... .
$(iv)$ The number of bonds between atoms joined by a covalent bond is called .......... .

Oxygen molecule is paramagnetic because

The ion that is isoelectronic with $CO$ is

Give the number of electrons in the species $H_2^+$,$H_2$,and $O_2^+$.