Question

The d-electron configuration of $ C{{r}^{2+}},M{{n}^{2+}},F{{e}^{2+}} $ and $ C{{o}^{2+}} $ are $ {{d}^{4}},{{d}^{5}},{{d}^{6}} $ and $ {{d}^{7}} $ respectively. Which one of the following will exhibit minimum paramagnetic behaviour? $ \left[ At.no.Cr=24,Mn=25,Fe=26,Co=27 \right] $

• A. $ {{[Fe{{({{H}_{2}}O)}_{6}}]}^{2+}} $
• B. $ {{[Co{{({{H}_{2}}O)}_{6}}]}^{2+}} $
• C. $ {{[Cr{{({{H}_{2}}O)}_{6}}]}^{2+}} $
• D. $ {{[Mn{{({{H}_{2}}O)}_{6}}]}^{2+}} $

Answer 1

Answer: (B)

$ \therefore $ $ {{[Co{{({{H}_{2}}O)}_{6}}]}^{2+}} $ has minimum number of unpaired electrons and thus minimum paramagnetic behaviour.