Multiple choice Primary valency of iron in K4 [Fe (CN)6] is 2 3 4 5 Reveal answer Fill a bubble to check yourself A Correct answer Explanation In K4[Fe(CN)6], the primary valency corresponds to the oxidation state of the central metal ion. Since the total charge of the complex is 0 and CN is -1, Fe + 6(-1) = -4, so Fe = +2.