K i.e. pottSium is a member of group 1 so it readily reacts with oxygen.
As we move down the group the tendency of forming peroxides and super oxides increase. KO2 is pottasium super oxide ko2 =k+ + O2( 1-) .
O2 (1-) is super oxide in which o has a charge of -1/2.
ko2 =+1×1 + x (oxidation state of oxygen )×2=0 (as ko2 is electrically neutral)
=> x= -1/2