Question

Assertion : $[Fe(H_{2}O{)}_6{]}^{3+}$ is strongly paramagnetic whereas $[Fe(CN{)}_6{]}^{3-}$ is weakly paramagnetic.
Reason : $H_{2}O$ is a weak field ligand and $C{N}^{-}$ is a strong field ligand.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

Answer: (A)

${\left[Fe(CN{)}_6\right]}^{3-}\Rightarrow C\bar{N}\Rightarrow$ Strong field ligand.
$F{e}^{3+}=[\text{Ar}]3d^5($ Refer $o$ image o1)
1. 1 unpaired electrons.
2. Weakly paramagnetic
${\left[Fe{\left(H_{2}O\right)}_6\right]}^{3+}\Rightarrow H_{2}O\Rightarrow$ Weak field ligand.
$\Rightarrow F{e}^{3+}\Rightarrow [Ar]3d^5$ (Refer o image o2)
5 unpaired electrons.
${\left[Fe{\left(H_{2}O\right)}_6\right]}^{2+}=$ Strong paramagnetic.