Q30 / 180 · KCET 2007 · Chemistry

The oxidation state of iron in $\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$ is

  • A
    1
  • B
    4
  • C
    3
  • Correct answer
    D
    2

Solution

Let the oxidation state of iron in $\mathrm{K}_{4}\left[\mathrm{Fe}\left(\mathrm{CN}_{6}\right]\right.$ is $x$ $\begin{aligned} 4(+1)+x+6(-1) &=0 \\ 4+x-6 &=0 \\ x &=+2 \\ \mathrm{Au}+8 \mathrm{CN}^{-}+2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2} \longrightarrow & \underset{\text { Soluble }}{\longrightarrow} \\ 2\left[\mathrm{Au}(\mathrm{CN})_{2} \Gamma+\mathrm{Zn} \longrightarrow\right.& \mathrm{Au}(s) \downarrow+\left[\mathrm{Zn}(\mathrm{CN})_{4}\right]^{2-} \end{aligned}$

Hence, the correct answer is option: 'D'.

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