Which one of the following complexes is an outer orbital complex?

The molecule in which hybrid $MOs$ involve only one $d-$orbital of the central atom is:

Which of the following complexes formed by $Nickel$ is tetrahedral and paramagnetic?

What is the geometry of the $[Ni(CO)_4]$ complex?

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 . . . . . . .

In $[Pt(NH_3)_2Cl_2]$,the $Pt-Cl$ bond length is $2 \ \mathring{A}$ and the $Cl-Cl$ distance is $2.88 \ \mathring{A}$. What is the geometry of the compound?