Question

Determine the oxidation number of the underlined element in each of the following.

a) O ₂   ​b) Ag NO₃​ c) MnO₂   ​ d) ZnSO₄ e) ClO_3- ​ f) CO_3^2- g) KMnO₄​ h) MgSO₃ i) Na_​2​ S ₂ O₃

Answer 1

1) O2

Let the oxidation number of O is x

so 2x = 0

x= 0

so oxidation number will be 0

b) Ag NO₃​

Let the oxidation number of Ag = x

x + (-5) + 3(-2) =

x = 1

c) MnO₂   ​

Let oxidation number of Mn = x   

x + 2(-2) = 0

x = +4

d) ZnSO₄

Let oxidation number of Zn = x   

x + 6 + 4(-2)

x = +2

e) ClO_3- ​

Let oxidation number of Cl = x

x + 3(-2) = -1

x = +5

f) CO_3^2-

Let oxidation number of C = x   

x + 3(-2) = -2

x = +4

g) KMnO₄​

Let oxidation number of Mn = x   

+1 + x + 4(-2)

x = +7

h) MgSO₃

Let oxidation number of S = x   

+2 + x + 3(-2)

x = +4

i) Na_​2​ S ₂ O₃

Let oxidation number of S = x   

2(+1) + 2x + 3(-2) = 0

x = +2