Which of the following complexes has a shape different from the others?

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 . . . . . . .

Consider that a $d^{6}$ metal ion $(M^{2+})$ forms a complex with aqua ligands,and the spin-only magnetic moment of the complex is $4.90 \ BM.$ The geometry and the crystal field stabilization energy $(CFSE)$ of the complex are:

The hexachloridocobaltate $(III)$ ion is a high-spin complex. What is the possible hybridisation state of the cobalt ion in this complex?

$A$ coordination compound is made of $Co^{3+}$,$NH_3$,and $Cl^{-}$. $A$ $0.1 \ M$ solution of this complex when treated with excess silver nitrate gave no precipitate. The formula of the complex and secondary valency of metal are respectively.

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