Among the statements a - d , the incorrect ones are: a Octahedral C o I I I complexes with strong field…

1. $\left(\mathrm{a}\right)$ and $\left(\mathrm{d}\right)$ only
2. $\left(\mathrm{c}\right)$ and $\left(\mathrm{d}\right)$ only
3. $\left(\mathrm{a}\right)$ and $\left(\mathrm{b}\right)$ only
4. $\left(\mathrm{b}\right)$ and $\left(\mathrm{c}\right)$ only

Solution

So if there are strong field ligands in complex, pairing of electrons will take place, due to which number of unpaired electrons decrease due to which magnetic moment decrease.
$\left(\mathrm{c}\right)$ Splitting power of ethylenediamine (en) is greater than fluoride $\left({\text{F}}^{-}\right)$ ligand therefore more energy absorbed by ${\left[\text{Co}\left(\text{en}\right)\right]}^{3+}$ as compared to  ${\left[{\text{CoF}}_{\text{6}}\right]}^{3-}$

So wave length of light absorbed by ${\left[\text{Co}\left(\text{en}\right)\right]}^{3+}$ is lower than that of ${\left[{\text{CoF}}_{\text{6}}\right]}^{3-}$

$\text{(d) }{\mathrm{\Delta }}_{\mathrm{t}}=\frac{4}{9}{\mathrm{\Delta }}_0$

$\text{so if }{\mathrm{\Delta }}_0=18,000 {\text{cm}}^{-1}$

${\mathrm{\Delta }}_{\text{t}}=\frac{4}{9}\times 18000=8000 {\text{cm}}^{-1}$

Statement $\left(\mathrm{a}\right)$ and $\left(\mathrm{d}\right)$ are incorrect.

Asked in: MHT CET Full Test 2

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