$(I)\, [Ni(CN)_4]^{2-}\,\,\,(II)\, [NiCl_4]^{2-}\,\,\,(III)\,Ni(CO_4)\,\,\,$
$(IV)\, [Ni(H_2O)_6 ]^{2+}$
\(\left[ NiCl _4\right]^{2-}\) and \(\left[ Ni ^2\left( H _2 O \right)_6\right]^{2+}\) contain 2 unpaired electrons each. Thus they are paramagnetic and will be attracted by the magnetic field.
In \(\left[ Ni ( CN )_4\right]^{2-}\) and \(\left[ Ni ( CO )_4\right]\), all the electrons are paired. Hence, they are diamagnetic substances and are not attracted by the magnetic field.
$(A)$ $\left. Na _{4}\left[ Fe ( CN )_{5} NOS \right)\right]$
$(B)$ $Na _{4}\left[ FeO _{4}\right]$
$(C)$ $\left[ Fe _{2}( CO )_{9}\right]$
સંકીર્ણ $-$ નામ