Question

Oxidation state of nitrogen in H-N = C is
(1) - 4
(3) -3
(2) + 3
(4) -2

​

Answer 1

You use the rules for oxidation numbers to calculate that the oxidation number of

N

is +5.

Explanation:

The important rules here are:

The oxidation number of oxygen in a compound is usually -2, except in peroxides, where it is -1.

The sum of all the oxidation numbers in a polyatomic ion is equal to the charge on the ion.

The formula of nitrate ion is

NO

-

3

.

Rule 1 tells us that the oxidation number of

O

is -2:

[

N

-2

O

3

]

-

.

The three

O

atoms have a total oxidation number of -6.

Rule 2 tells us that the sum of all the oxidation numbers equals the charge on the ion.

Let

x

= the oxidation number of

N

.

x

+

(

-6

)

=

-1

x

=

-1

−

(-6)

=

-1 + 6

=

+

5

∴ The oxidation number of

N

is +5:

[

+5

N

-2

O

3

]

-

.