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

1. NH2OH

2. NH4NO3

3. N2H4

4. N3H

Hint: Compound in which nitrogen present in cationic part as well as anionic part.
NH4NO3 is actually NH4+ and NO3-. It is an ionic compound.
The oxidation state of nitrogen in the two species is different as shown below
Let, oxidation number of N in N+H4 is
or x+4=+1 or x=-3
Let, oxidation number of N in NO3- is x
x+(3×-2)=-1 or x-6=-1 or x=+5