Among the following species,the diamagnetic molecule is

Which of the following has unpaired electron$(s)$?

Given below are two statements:
Statement $I$: $A$ $\pi$ bonding $MO$ has lower electron density above and below the inter-nuclear axis.
Statement $II$: The $\pi^*$ antibonding $MO$ has a node between the nuclei.
In the light of the above statements,choose the most appropriate answer from the options given below:

The bond order of $O_2^{+}$ is $x$. The bond orders of $O_2^{-}$ and $O_2^{2+}$ are respectively

According to molecular orbital theory,the paramagnetism of the $O_2$ molecule is due to the presence of

The sum of bond order of $O_2^{+}$,$O_2^{-}$,$O_2$ and $O_2^{2+}$ is equal to