Does peroxide ion have any unpaired electrons?

![enter image description here](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b1/MO-Peroxid.png/1280px-MO-Peroxid.png)
According to the MOT diagram there are no unpaired electrons but in an exam I gave the answer key said it has 2 unpaired electrons. I can also find some images on google where it has 2 unpaired electrons.


![enter image description here](https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSRQLClr0v6zqBiGFtHQ_ziyMfzLMUNr0P67A8joOJnc52KK5C7)


Which one is correct and why?




The MO diagram you show is correct. $O\_2^{2-}$ has a bond order of 1 (equivalent to a single bond between the two O atoms) as the antibonding $\pi^\*$ orbitals contain 4 electrons and this cancels the $\pi$ orbitals' 4 bonding electrons. See the Mo diagrams for the different $O\_2$ species below:


[![enter image description here](https://i.stack.imgur.com/8ait6.png)](https://i.stack.imgur.com/8ait6.png)


<https://www.chem.uci.edu/~lawm/Ch%205%20Solutions.pdf>


The Lewis diagram is incorrect. It shows the O atoms with an expanded octet (not allowed for period 2 elements by the rules of Lewis diagrams) and it shows the bond between the two O atoms as a double, rather than the measured single O-O bond length:


[![enter image description here](https://i.stack.imgur.com/VCWtp.png)](https://i.stack.imgur.com/VCWtp.png)


<http://www.wiredchemist.com/chemistry/data/oxygen-selenium-compounds>


It also shows the peroxide ion as having unpaired electrons, when it is actually diamagnetic. It should look like this:


[![enter image description here](https://i.stack.imgur.com/Ah3qC.png)](https://i.stack.imgur.com/Ah3qC.png)


<https://en-journal.org/ViewImage.php?Type=F&aid=489334&id=F1&afn=142_EN_24_4_325&fn=en-24-325-g001_0142EN>


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