I have to fill in the blanks of these questions with the elements H (hydrogen), Co (cobalt), Ga (gallium), and O (oxygen), but different sources are telling me different things:

Question

7. Its most common oxidation state is -2

8. A metal with more than one oxidation state

9. Metal with an oxidation number of +3

10. Has oxidation numbers of +1 and -1

Does anyone know which element goes with which criteria? Any help is greatly appreciated! :D

Answer 1

I hope those different sources are not from this forum
I have to fill in the blanks of these questions with the elements H (hydrogen), Co (cobalt), Ga (gallium), and O (oxygen), but different sources are telling me different things:

7. Its most common oxidation state is -2
Most likely oxygen. -2 is most common but it does have -1 in peroxides and -1/2 in superoxides.

8. A metal with more than one oxidation state
Most likely Co since +2 and +3 are common. H and O don't count as answers since they are not metals. So it must be between Co and Ga and Ga is +3. Other oxidation states of Ga are not common.

9. Metal with an oxidation number of +3
Most likely Ga. See 8 above.

10. Has oxidation numbers of +1 and -1
H must go here. +1 is the more common oxidation state but -1 is present in hydrides.
I would take these answers to the bank. :-)

Answer 2

Thanks so much!!!! :D