Question

Which of the following statements is not correct about the reaction given below?
$K_4\left[Fe{\left(CN\right)}_6\right]\stackrel{Oxidation}{\to }{Fe}^{3+}+C{O}_2+N{O}_3^{\ominus }$

• A. $Fe$ is oxidised from ${Fe}^{2+}$ to ${Fe}^{3+}$
• B. Carbon is oxidised from $C^{2+}$ to $C^{4+}$
• C. $N$ is oxidised from $N^{3-}$ to $N^{5+}$
• D. Carbon is not oxidised

Answer 1

Answer: (D)

Carbon is not oxidised

Oxidation state of C in complex $K_4\left[Fe\right(CN{)}_6]$ is same as that of $\left[Fe\right(CN{)}_6{]}^{4-}$

Now , the carbon is in the form of $C{N}^{-}$. Let the oxidation state of C be $x$.

$x+(-3)=-1$
$x=3-2=+2$.

Now in $C{O}_2$,
$x+2(-2)=0$
$x=+4$.

So the change in oxidation state of C is by 2.
So carbon is oxidised from $C^{+2}$ to $C^{+4}$
Hence, D option is incorrect.