Which of the following species is paramagnetic?

Correct decreasing order of bond order of oxygen species in $I$ to $IV$:
$(I)$ $Na_2O_2$
$(II)$ $O_2[AsF_6]$
$(III)$ $CsO_2$
$(IV)$ $O_2$

Which of the following molecules does not exist according to molecular orbital theory?

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

According to the molecular orbital theory,the bond order in $C_2$ molecule is

If $P$ to $T$ are second period $p-$block elements,then which of the following graphs shows the correct relation between the number of valence electrons in $P_2$ to $T_2$ (corresponding molecules) and their bond order?