Potassium hexacyanidoferrate(III) contains the complex anion with six cyanide ligands (CN-). Which option correctly gives its formula, the oxidation number of Fe, and the TOTAL number of atoms in one formula unit?

JEE Advanced levelSingle correct optionDifficulty 3 of 3bn042

Potassium hexacyanidoferrate(III) contains the complex anion with six cyanide ligands ( $CN X^{-}$ ). Which option correctly gives its formula, the oxidation number of Fe, and the TOTAL number of atoms in one formula unit?

Fe(III) with six

CN X^{-}

gives the anion charge

+ 3 - 6 = - 3

, so three K are needed:

K X_{3} [Fe (CN) X_{6}]

. Atoms:

3 + 1 + 6 + 6 = 16

(3 K, 1 Fe, 6 C, 6 N).