Question

What is the oxidation number of $\mathrm{N}$ in ${\mathrm{HNO}}_3$?

Answer 1

Oxidation number: Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element.

Calculating the oxidation number of Nitrogen(N) in ${\mathrm{HNO}}_3$:

The oxidation state of Hydrogen(H) = +1

The oxidation state of Oxygen(O) = -2

Consider the oxidation state of nitrogen(N) = x

Now,

$$\begin{gathered} +1+\mathrm{x}+\left(-2\times 3\right)=0 \\ \mathrm{x}=6-1 \\ \mathrm{x}=+5 \end{gathered}$$

Hence, the oxidation number of $\mathrm{N}$ in ${\mathrm{HNO}}_3$ is $+5$.