Question

The number of geometric isomers that can exist for square planar [Pt (Cl) (py) (NH3) (NH2OH)]+ is (py = pyridine) :?

Answer 1

I think only 3 isomers are available for square planar `ML_1L_2L_3L_4`.

Explanation:

You should draw these out to convince yourself that this is the case. I don't think these have been demonstrated in a model system (it would be difficult coordination chemistry to accomplish!).