Which of the following complexes is an outer orbital complex?

Which one of the following is an inner orbital complex?

$[NiCl_{4}]^{2-}$ is paramagnetic while $[Ni(CO)_{4}]$ is diamagnetic though both are tetrahedral. Why?

The hybridization involved in the complex $[Ni(CN)_4]^{2-}$ is (Atomic number of $Ni = 28$):

What type of hybridization is exhibited by $[CoF_6]^{3-}$?

The number of isoelectronic species among $Sc^{3+}$, $Cr^{2+}$, $Mn^{3+}$, $Co^{3+}$, and $Fe^{3+}$ is $n$. If $n$ moles of $AgCl$ are formed during the reaction of the complex with the formula $CoCl_{3}(en)_{2}NH_{3}$ with excess $AgNO_{3}$, then the number of electrons present in the $t_{2g}$ orbital of the complex is . . . . . . .