Question

The oxidation state of $S$ in $H_2{S}_2{O}_8$ is

• A. +7
• B. +6
• C. +2
• D. -2

Answer 1

The correct option is B

+6

By usual method :$H_2{S}_2{O}_8$
$1\times 2+2x+8\times (-2)=0$
$\Rightarrow$ 2x = +16 - 2 = 14 OR x = +7

Marshall's acid (the given compound) also has a peroxide linkage. Here S shows +6 oxidation state

Therefore the evaluation of oxidation state of sulphur should be made as follows:

$2\times (+1)+2\times \left(X\right)+6\times (-2)+2\times (-1)=0$