9.29     Amongst the following ions which one has the highest magnetic moment value?                 $(i)[Cr(H_{2}O)_{6}]^{3+}$            $(ii)[Fe(H_{2}O)_{6}]^{2+}$            $(iii)[Zn(H_{2}O)_{6}]^{2+}$

(i) No. of unpaired electrons in $[Cr(H_{2}O)_{6}]^{3+}$ is 3.

The magnetic moment is given by :

$=\ \sqrt{n(n+2)}$

or                                                                       $=\ \sqrt{3(3+2)}\ =\ \sqrt{15}BM$

(ii) Similarly in   $[Fe(H_{2}O)_{6}]^{2+}$ the number of unpaired electrons is 4.

So the magnetic moment :

$=\ \sqrt{4(4+2)}\ =\ \sqrt{24}BM$

(iii) In the case of    $[Zn(H_{2}O)_{6}]^{2+}$   the number of unpaired electrons is 0. So its magnetic moment is also zero.

Thus   $[Fe(H_{2}O)_{6}]^{2+}$  has the highest dipole moment among all.

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