Which one of the following does not exhibit paramagnetism?

Compare the relative stability of the following species and indicate their magnetic properties: $O_2$,$O_2^+$,$O_2^-$ (superoxide),$O_2^{2-}$ (peroxide).

The bond lengths of diatomic molecules of elements $X$,$Y$ and $Z$ respectively are $143 \text{ pm}$,$110 \text{ pm}$ and $121 \text{ pm}$. The atomic numbers of $X$,$Y$ and $Z$ respectively are:

Pair of species among the following having same bond order as well as paramagnetic character will be -

In $Cl_2O_7$,the $\pi$-bond between $Cl$ and $O$ is formed by the overlapping of :-

The bond order of $O_2^+$ is the same as in