Question

Choose the option where the oxidation number of the metals is +3:

• A. $MgW{O}_4$
• B. $Fe(CO{)}_5$
• C. $K_3\left[Fe\right(CN{)}_6]$
• D. None of the above

Answer 1

The correct option is C $K_3\left[Fe\right(CN{)}_6]$

A) $MgW{O}_4$ Oxidation number is 1(+2)+x+4(-2) =0,i.e x=8-2 i.e +6

B) $Fe(CO{)}_5$ oxidation state of Fe in Fe (CO5) is 0 because CO is a neutral ligand and does not contribute to charge so Fe is in its natural state with oxidation number = 0

C) $K_3\left[Fe\right(CN{)}_6]$ Oxidation number is 1(+3)+x+6(-1) =0,i.e x=6-3 i.e +3. So the compound with oxidation number +3 is $K_3\left[Fe\right(CN{)}_6]$

Hence option C is correct.