Which of the following species is paramagnetic?

The number of geometric isomers that can exist for the square planar complex $[Pt(Cl)(py)(NH_3)(NH_2OH)]^+$ is ($py=$ pyridine):

An octahedral complex having molecular composition $Co \cdot 5NH_3 \cdot Cl \cdot SO_4$ has two isomers $A$ and $B$. The solution of $A$ gives a white precipitate with $AgNO_3$ solution and the solution of $B$ gives a white precipitate with $BaCl_2$ solution. The type of isomerism exhibited by the complex is,

Which of the following complex compounds will exhibit highest paramagnetic behaviour?
(At. No. $Ti = 22, Cr = 24, Co = 27, Zn = 30$)

Which one of the following complexes shows optical isomerism? $(en = \text{ethylenediamine})$

Which of the following does not have optical isomers?