The oxidation state of nitrogen in option A, H2N2O2, is given incorrectly.
In H2N2O2, the oxidation state of oxygen is -1, and there are two oxygen atoms, so the total oxidation state contributed by oxygen is -2. The overall molecule has a neutral charge, which means the total oxidation state contributed by all the atoms must be 0.
Let x be the oxidation state of nitrogen. Then, we can set up the equation:
2(1) + x + (-2) + (-2) = 0
where the first term is the oxidation state of hydrogen (which is always +1) multiplied by the number of hydrogen atoms, and the second and third terms are the oxidation state of oxygen (which is always -2) multiplied by the number of oxygen atoms.
Simplifying the equation, we get:
x - 2 = 0
x = +2
Therefore, the oxidation state of nitrogen in H2N2O2 is +2, not +1 as given in option A.