Correct order of molar extinction coefficient values of the visible absorption bands for the following… · ABC26IN0147
Subject: Inorganic Chemistry · Chapter: Coordination Chemistry · Topic: Coordination Chemistry – General · Exam: CSIR NET 2019 · Marks: 2 · Difficulty: Hard
Correct order of molar extinction coefficient values of the visible absorption bands for the following species is
(a)$[\mathrm{Cr(H_2O)_6}]^{2+} > [\mathrm{Mn(H_2O)_6}]^{2+} >$ Chlorophyll $> [\mathrm{NiCl_4}]^{2-}$
(b)Chlorophyll $> [\mathrm{NiCl_4}]^{2-} > [\mathrm{Cr(H_2O)_6}]^{2+} > [\mathrm{Mn(H_2O)_6}]^{2+}$
(c)$[\mathrm{NiCl_4}]^{2-} >$ Chlorophyll $> [\mathrm{Cr(H_2O)_6}]^{2+} > [\mathrm{Mn(H_2O)_6}]^{2+}$
(d)Chlorophyll $> [\mathrm{Cr(H_2O)_6}]^{2+} > [\mathrm{NiCl}]^{2-} > [\mathrm{Mn(H_2O)_6}]^{2+}$
Answer
Answer: B ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
Molar absorptivity: chlorophyll's π→π* bands (ε ~ 10⁵) > tetrahedral [NiCl₄]²⁻ (no centre of symmetry, ε ~ 10²) > [Cr(H₂O)₆]²⁺ (spin-allowed, Laporte-forbidden d–d, ε ~ 10) > [Mn(H₂O)₆]²⁺ (spin- and Laporte-forbidden, ε ~ 0.1).
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