Question

Velence bond theroy describes the bonding in complexs in terms of coordinate -covalent bond resulting from overlap filled ligand orbitals with vacant metal hybrid orbitals This theory explains magnetic behaviour and geometrical shape of coordination compounds Magnetic moment of a complex compound can be determined experimentally and theoretically by using spin only formula
Magnetic moment `sqrtn (n+2)BM` (where n = No. unpaired electrons) .
`Ni^(2+)` cation combines with a uninegative monodentate ligand `X^(Θ)` to form paramagnetic complex `[NiCI_(4)]^(2-)` The number of unpaired electrons(s) in central metal cation and geometry of this complex respectively are
(a) One,tetrahedral
(b) Two,tetrahedral
(c ) One,square planar
(d) Two, square planar .

Answer 1

Correct Answer - B
`Ni^(2+) i n [NiCI_(4)]^(2-)`
`Ni(Z=28)implies3d^(8)4s^(2)`
`Ni^(2+)implies3d^(8) 4_(s)^(0)`
Hybridisation implies `sp^(3)`
Shape =Tetrahedral
`mu_(eff) = sqrt8 = 2.89BM` .