Question

The oxidation number of arsenic atom in H3AsO4 is :

(A) –5

(B) +1

(C) –3

(D) +5

Explanation would be appreciated :)

Answer 1

$<b><font face=copper black size=4 colour=purple>$Given :

$\mathsf{H_3AsO_4}$

Oxidation number of H = + 1

Oxidation number of O = - 2

Now,

Let,

Oxidation number of As = x

So,

Overall charge on the compound = 0

•°•

x + 3 ( + 1 ) + 4 ( - 2 ) = 0

x + 3 - 8 = 0

x - 5 = 0

x = + 5

Hence, Option (D) is correct.

^^"

Answer 2

Hey dear,

● Answer -
(D) +5.

● Explanation -
Let m be oxidation number of As in H3AsO4.

We know, the sum of oxidation numbers of all entities is equal to total charge on compound.
3(+1) + 1(m) + 4(-2) = 0
3 + m - 8 = 0
x - 5 = 0
m = +5

Hence, oxidation number of As in H3AsO4 is +5.

Thanks.