question_answer

What is the magnetic moment of \[{{K}_{3}}[Fe{{F}_{6}}]\] [Orissa JEE 2005]

A) 5.91 BM

B) 4.89 BM

C) 3.87 BM

D) 6.92 BM

Correct Answer: A

Solution :

\[{{K}_{3}}[Fe{{F}_{6}}]\] \[F{{e}^{3+}}=[Ar]3{{d}^{5}}4{{s}^{0}}\] Number of unpaired electrons = 5 Magnetic moment \[=\sqrt{n(n+2)}=\sqrt{5(5+2)}\] \[=\sqrt{35}\]= 5.91 BM.