In which of the following compounds, an element exhibits two different oxidation states?

NH4NO3 is actually NH4+and NO3-. It is an ionic compound. The oxidation number of nitrogen in the two species is different.Let, oxidation number of N in NH4+ is.x.⇒ x + (4 x 1) = +1 or x +4= +1 or x= - 3Let oxidation number of N in NO3-is x.⇒ x+(3x-2) = -l or x-6 = -l or x = +5