The correct increasing order of stability of the complexes based on Δ 0 value is : (I) [ Mn ( CN ) 6 ] 3- (II) [ Co ( CN ) 6 ] 4- (III) [ Fe ( CN ) 6 ] 4- (IV) [ Fe ( CN ) 6 ] 3-

Chemistry · Coordination Compounds

JEE Main 2025 — 29 January, Morning Shift — Question 5

The correct increasing order of stability of the complexes based on $\Delta_{0}$ value is :

(I) $\left[\mathrm{Mn}(\mathrm{CN})_{6}\right]^{3-}$

(II) $\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{4-}$

(III) $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}$

(IV) $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}$

Option A:
II $<$ III $<$ I $<$ IV
Option B:
IV $<$ III $<$ II $<$ I
Option C:
I $<$ II $<$ IV $<$ III
Correct
Option D:
III $<$ II $<$ IV $<$ I

Answer: C

Step-by-step solution

(I) $\left[\mathrm{Mn}(\mathrm{CN})_{6}\right]^{3-}$ $-1.6 \Delta_{\text {o }}$ (II) $\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{4-} \quad-1.8 \Delta_{\mathrm{o}}$ (III) $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-} \quad-2.4 \Delta_{\mathrm{o}}$ (IV) $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-} \quad-2.0 \Delta_{\mathrm{o}}$

I $<$ II $<$ IV $<$ III

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Exam: JEE Main 2025
Paper: 29 January, Morning Shift
Subject: Chemistry
Chapter: Coordination Compounds
Topic: Theories of Bonding in Coordination Compounds

Match List-I with List-II. List-I (Complex) List-II (Hybridisation & Magnetic characters) --- --- (A) [ . MnBr 4 ]^2- (I) d^2 sp^3 \&…

Answer: C

Step-by-step solution

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