Question

Find the oxidation number of the elements in the following compounds.
a. $\text{C}$ in ${\text{CO}}_2$
b. $\text{Mn}$ in ${\text{MnSO}}_4$
c. $\text{N}$ in ${\text{HNO}}_3$ [3 Marks]

Answer 1

a. $\text{C}$ in ${\text{CO}}_2$
1 (C) + 2 (O) = 0
x + 2 × (-2) = 0
x - 4 = 0 ‘
x = 4 .
Oxidation number of $\text{C}$ in ${\text{CO}}_2$ is +4 [1 Mark]

b. $\text{Mn}$ in ${\text{MnSO}}_4$
1 (Mn) + 1 (S) + 4 (O) = 0
x + 1 × 6 + 4 × (-2) = 0
x + 6 – 8 = 0
x – 2 = 0
x = 2
Oxidation number of $\text{Mn}$ in ${\text{MnSO}}_4$ is +2
[1 Mark]

c. $\text{N}$ in ${\text{HNO}}_3$
1 (H) + 1 (N) +3 (O) = 0
1 × 1 + x + 3 × (-2) = 0
1 + x – 6 = 0
x – 5 = 0
x = 5
Oxidation number of $\text{N}$ in ${\text{HNO}}_3$ is +5 [1 Mark]