Answer:
+5
Explanation:
Let's consider the following balanced equation.
Mn(NO₃)₂ + 2 HCl --> MnCl₂ + 2 HNO₃
We can determine the oxidation number of N in (NO₃)₂²⁻ taking into account that the sum of the oxidation numbers of the elements present in a chemical species is equal to this overall charge. For this compound we know:
- The oxidation number of O is -2.
- The overall charge is 2-.
- We have 2 atoms of N and 2× 3 = 6 atoms of O.
2 N + 6 O = 2-
2 N + 6 (-2) = 2-
2 N = +10
N = +5
