Question

The oxidation number of sulphur in $H_2{S}_2{O}_7$ and iron in $K_{4}Fe(CN{)}_6$ is respectively

• A. + 6 and + 2
• B. + 2 and + 2
• C. + 8 and + 2
• D. + 6 and + 4

Answer 1

The correct option is A + 6 and + 2

$H_2{S}_2{O}_7$
$2\times (+1)+2\times x+7\times (-2)=0$
$+2+2x-14=0$
$2x=14-2=12$
$x=\frac{12}{2}=+6forS$
$K_{4}Fe(CN{)}_6$
$4\times (+1)x+6\times (-1)=0$
$4+x-6=0$
$x=6-4=+2forFe$.