question_answer

Which one of the following shows maximum value of paramagnetic behaviour?

A)  \[{{[Sc{{(CN)}_{6}}]}^{3-}}\]      

B)  \[{{[Co{{(CN)}_{6}}]}^{3-}}\]

C)  \[{{[Fe{{(CN)}_{6}}]}^{4-}}\]

D)         \[{{[Cr{{(CN)}_{6}}]}^{3-}}\]

Correct Answer: D

Solution :

Key Idea: Calculate the oxidation state of central metal ion as that gives idea of about number of unpaired or paired electrons. \[Sc=21=1{{s}^{2}}{{,}^{2}}{{s}^{2}}{{,}^{2}}{{p}^{6}}{{,}^{3}}{{s}^{2}},3{{p}^{6}},{{\,}^{4}}{{s}^{2}},{{\,}^{3}}{{d}^{1}}\] \[Ni(CN)_{4}^{2-}\] No unpaired electron hence, diamagnetic                 \[{{[Co{{(CN)}_{6}}]}^{3-}}\]                                                                                                 \[{{[Cr{{(CN)}_{6}}]}^{3-}}\]