The $[Cr(NH_3)_6]^{3+}$ ion is ...

In which of the following compounds does the central metal atom have the maximum number of unpaired $e^-$?

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 pairs of compounds has the same number of unpaired electrons?

The number of possible optical isomers for the complexes $MA_{2}B_{2}$ with $sp^{3}$ and $dsp^{2}$ hybridised metal atom,respectively,is.
Note : $A$ and $B$ are unidentate neutral and unidentate monoanionic ligands,respectively.

Which of the following pairs of complexes have the same magnetic moment,same hybridisation,and same $EAN$ value?