# Geometrical shapes of the complexes formed by the reaction

( mathrm{of} mathrm{Ni}^{2+} ) with ( mathrm{Cl}^{-}, mathrm{CN} ) and ( mathrm{H}_{2} mathrm{O}, ) respectively, are

(a) octahedral, tetrahedral and square planar

(b) tetrahedral, square planar and octahedral

(c) square planar, tetrahedral and octahedral

(d) octahedral, square planar and octahedral

( mathrm{Ni}^{2+}+4 mathrm{CN}^{-} rightarrowleft[mathrm{Ni}(mathrm{CN})_{4}right]^{2-} )

Here, ( mathrm{Ni}^{2+} ) has ( d^{8} ) -configuration with ( mathrm{CN} ) as strong ligand.

( d^{8} ) -configuration in strong ligand field gives ( d s p^{2} ) -hybridisation, hence square planar geometry.

[

mathrm{Ni}^{2+}+4 mathrm{Cl}^{-} longrightarrowleft[mathrm{NiCl}_{4}right]^{2-}

]

Here, ( mathrm{Ni}^{2+} ) has ( d^{8} ) -configuration with ( mathrm{Cl}^{-} ) as weak ligand

( d^{8} ) -configuration in weak ligand field gives ( s p^{3} ) -hybridisation, hence tetrahedral geometry.

( mathrm{Ni}^{2+} ) with ( mathrm{H}_{2} mathrm{O} ) forms ( left[mathrm{Ni}left(mathrm{H}_{2} mathrm{O}right)_{6}right]^{2+} ) complex and ( mathrm{H}_{2} mathrm{O} ) is a weak

ligand.

Therefore, ( left[mathrm{Ni}left(mathrm{H}_{2} mathrm{O}right)_{6}right]^{2+} ) has octahedral geometry.