Ncert Exercises & Solutions

Assertion (A):	${[Fe {(CN)}_{6}]}^{3 -}$ ion shows magnetic moment corresponding to two unpaired electrons.
Reason(R):	Because it has $d^{2} s p^{3}$ type hybridization.

1.	Both (A) and (R) are True and (R) is the correct explanation of (A).
2.	Both (A) and (R) are True and (R) is not the correct explanation of (A).
3.	(A) is True but the (R) is False.
4.	(A) is False but the (R) is True.

Hint: CN is a strong field ligand

According to VBT, the orbital diagram of Fe³⁺ in ${[Fe {(CN)}_{6}]}^{3 -}$ is

Hybridization = $d^{2} s p^{3}$

n=1

Hence, the correct assertion is ${[Fe {(CN)}_{6}]}^{3 -} ion shows magnetic moment corresponding to one unpaired electron .$

$i . e ., μ = \sqrt{n (n + 2)}$
$= \sqrt{1 (1 + 2)}$
$= \sqrt{3} = 1.73 BM$

Hence, the Assertion is false but the reason is true.