Question

Match the following complexes with their number of unpaired electrons:

List-I (Complex)		List-II (No. of unpaired electrons)
A) \([\mathrm{MnCl}_6]^{3-}\)		I) 5
B) \([\mathrm{FeF}_6]^{3-}\)		II) 2
C) \([\mathrm{Mn(CN)}_6]^{3-}\)		III) 0
D) \([\mathrm{Co(C}_2\mathrm{O}_4)_3]^{3-}\)		IV) 4

• A. A-II, B-IV, C-III, D-I
• B. A-IV, B-II, C-I, D-III
• C. A-III, B-I, C-IV, D-II
• D. A-IV, B-I, C-II, D-III

Hint:

Nature of ligand affects crystal field splitting and number of unpaired electrons.

Answer 1

The Correct Option is D

- \([\mathrm{MnCl}_6]^{3-}\): high spin, 4 unpaired electrons.
- \([\mathrm{FeF}_6]^{3-}\): high spin, 5 unpaired electrons.
- \([\mathrm{Mn(CN)}_6]^{3-}\): low spin, 2 unpaired electrons.
- \([\mathrm{Co(C}_2\mathrm{O}_4)_3]^{3-}\): low spin, 0 unpaired electrons.