The complexes $[Co(NH_3)_5Br]SO_4$ and $[Co(NH_3)_5SO_4]Br$ are examples of which type of isomerism?

Which one of the following complexes is paramagnetic?

Which one of the following complexes exhibits chirality?

Which of the following pairs has the same magnetic moment?

On treatment of $[Ni(NH_3)_4]^{2+}$ with concentrated $HCl,$ two compounds $I$ and $II$ having the same formula,$Ni(NH_3)_2Cl_2$ are obtained. $I$ can be converted into $II$ by boiling with dilute $HCl.$ $A$ solution of $I$ reacts with oxalic acid to form $[Ni(NH_3)_2(C_2O_4)]$ whereas $II$ does not react. Point out the correct statement of the following:

Which of the following complexes exhibits both geometrical and optical isomerism? $(en = \text{ethylenediamine})$