Which of the following hybrid states is associated with a low spin octahedral complex?

An octahedral complex of $Co^{3+}$ is diamagnetic. The hybridisation involved in the formation of the complex is

When $Ag^{+}$ reacts with excess of sodium thiosulphate,the obtained species having charge and geometry respectively will be?

In the complex $cis-[Cr(en)_2Cl_2]^+$,the oxidation state of $Cr$,the type of $d$-orbital involved in the valence shell,and the coordination number are respectively:

Match List-$I$ with List-$II$:

List-$I$ (Complexes)	List-$II$ (Hybridisation)
$A$. $[Ni(CO)_4]$	$I$. $sp^3$
$B$. $[Cu(NH_3)_4]^{2+}$	$II$. $dsp^2$
$C$. $[Fe(NH_3)_6]^{2+}$	$III$. $sp^3d^2$
$D$. $[Fe(H_2O)_6]^{2+}$	$IV$. $d^2sp^3$

Both $[Ni(CO)_4]$ and $[Ni(CN)_4]^{2-}$ are diamagnetic. The hybridization of nickel in these complexes,respectively,are