Explanation

(a)
$\left\lbrack Ni(CN)_{4} \right\rbrack^{2 -}$ion has $dsp^{2}$ hybridisation, zero magnetic moment and square planar structure. $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3d$ 4$s$ $4p$
[table] ⥮ | ⥮ | ⥮ | $\upharpoonleft$ | $\upharpoonleft$ | | ⥮ | | | | [/table]
Ni-atom
[table] ⥮ | ⥮ | ⥮ | $\upharpoonleft$ | $\upharpoonleft$ | | | | | | [/table]
Ni (II)
[image:9_image254.emf]
It has no unpaired electrons hence, its magnetic moment is zero.