An oxoacid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bond to oxygen that can dissociate to produce H+ cation and the anion of the acid. For example
oxoacids of nitrogen are :
HNO3
oxoacids of chlorine:
HCLO
As we can see only oxygen and hyrogen are attached to the main element hence these compounds are termed as oxoacids.
and acid proton are H+ ion which will get from acid .hhydroxide ion OH-.