Question

In which of the following pairs, the oxidation states of sulphur and chromium are same?

• A. $S{O}_3^{2-},Cr{O}_4^{2-}$
• B. $S{O}_3,Cr{O}_4^{2-}$
• C. $S{O}_2,Cr{O}_4^{2-}$
• D. $S{O}_2,C{r}_2{O}_7^{2-}$

Answer 1

The correct option is B $S{O}_3,Cr{O}_4^{2-}$

Oxidation number of oxygen is $-2$. Therefore,

In $S{O}_3^{-2}$,oxidation number of sulphur is $x+3(-2)=-2,x=+4$

In $Cr{O}_4^{-2}$,oxidation number of chromium is $x+4(-2)=-2,x=+6$

In $S{O}_3$,oxidation number of sulphur is $x+3(-2)=0,x=+6$

In $S{O}_2$,oxidation number of sulphur is $x+2(-2)=0,x=+4$

In $C{r}_2{O}_7^{-2}$,oxidation number of chromium is $2\left(x\right)+7(-2)=-2,x=+6$

So B) is correct pair having same oxidation state of sulphur and chromium.