Question

Oxidation number of $Cr$ in $KCr{O}_4^{-}$ is:

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

Answer 1

The correct option is B $+6$

Let x be the oxidation number of Cr in $KCr{O}_4^{-}$

$+1+X+4(-2)=-1$

$+1+X-8=-1$

$X-7=-1$

$X=+6$

Thus, the oxidation number of Cr in $KCr{O}_4^{-}$ is +6.

Option B is correct.