Bond order of $O_2$ is

Which one of the following is paramagnetic?

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:

Which of the following species is the least stable?

Which of the following species,$O_2$,$O_2^+$,and $O_2^-$,has the lowest bond order?

The lowest $O-O$ bond length in the following molecules is: