The one that is not expected to show isomerism is:
(1) [Ni(NH3)2Cl2]
(2) [Ni(NH3)4(H2O)2]2+
(3) [Ni(en)3]2+
(4) [Pt(NH3)2Cl2]
Ans. (1) [Ni(NH3)2Cl2]
Sol. (1) [Ni(NH3)2Cl2] $\implies$ Ni2+ $\implies$ 3d84s0.
$\implies$ sp3 hybridisation.
$\implies$ tetrahedral.
so [Ni(NH3)2Cl2] do not show isomerism.
(2) [Ni(NH3)4(H2O)2]2+, show geometrical isomerism.
(3) [Ni(en)3]2+, show optical isomerism.
(4) [Pt(NH3)2Cl2], show geometrical isomerism.