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JEE Mains · Chemistry · STD 12 - 5. Co-ordination chemistry

The correct order of the spin-only magnetic moments of the following complexes is \((I)\) \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{Br}_{2}\) \((II)\) \( \mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) \((III)\) \(\mathrm{Na}_{3}\left[\mathrm{Fe}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]\left(\Delta_{0}>\mathrm{P}\right)\) \((IV)\) \(\left(\mathrm{Et}_{4} \mathrm{N}\right)_{2}\left[\mathrm{CoCl}_{4}\right]\)

  1. A \((III) > (I) > (II) > (IV)\)
  2. B \((I) > (IV) > (III) > (II)\)
  3. C \((\mathrm{II}) \approx(\mathrm{I})>(\mathrm{IV})>(\mathrm{III})\)
  4. D \((\mathrm{III})>(\mathrm{I})>(\mathrm{IV})>(\mathrm{II})\)
Verified Solution

Answer & Solution

Correct Answer

(B) \((I) > (IV) > (III) > (II)\)

Step-by-step Solution

Detailed explanation

\((I)\;\;\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}\) \(\mathrm{Cr}^{+2} \Rightarrow[\mathrm{Ar}] 3 \mathrm{d}^{4}\) \(\mathrm{H}_{2} \mathrm{O} \rightarrow\) Weak field ligand \(\text { Unpaired } \mathrm{e}^{-}=4\)…