Q. Which of the following statements is incorrect?
A) In $K_{3}\lbrack Fe(CN)_{6}\rbrack$, the ligand has satisfied only the secondary valency of ferric ion.
B) In $K_{3}\lbrack Fe(CN)_{6}\rbrack$, the ligand has satisfied both primary and secondary valencies of ferric ion.
C) In $K_{4}\lbrack Fe(CN)_{6}\rbrack$, the ligand has satisfied both primary and secondary valencies of ferrous ion.
D) In$\left\lbrack Cu\left( {NH}_{3} \right)_{4} \right\rbrack{SO}_{4}$, the ligand has satisfied only the secondary valenecy of copper.
Explanation
(a)
Primary valency of metal is satisfied only by the anion. It is simply ionic valency. While secondary valency is satisfied by ligands (which can give a lone pair of electron). The ligands satisfying secondary valency, are always written in coordination sphere. This concept was given by Werner.
In $K_{3}\lbrack Fe(CN)_{6}\rbrack$, the $CN^{-}$ ions satisfy both the primary as well as secondary valency of ${Fe}^{3 +}$ ion.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.