What is the minimum oxidation state for the elements of the nitrogen subgroup. in what substances is it manifested?

Consider compounds containing nitrogen and find the lowest oxidation state of nitrogen.
For nitric acid HNO3, the oxidation state of nitrogen is as follows
+ 1 + x + 3 × (- 2) = 0
1 + x – 6 = 0
x = 5
The oxidation state of nitrogen is + 5.
For NO2
x + 2 (- 2) = 0
x – 4 = 0
x = 4
Therefore, the oxidation state is + 4.
For NO.
x + (- 2) = 0
x – 2 = 0
x = 2
The oxidation state is + 2.
For N2O.
2x + (-2) = 0
2x – 2 = 0
x = 1
The oxidation state is + 1.
For H3N.
1 × 3 + x = 0
3 + x = 0
x = – 3
The oxidation state is – 3.
This means that the lowest oxidation state of nitrogen is – 3.