Identify the number of unpaired electrons present and the geometry,respectively,of the complex $[CoF_6]^{3-}$ (given atomic number of $Co = 27$).

Addition of excess aqueous ammonia to a pink coloured aqueous solution of $MCl_2 \cdot 6H_2O (X)$ and $NH_4Cl$ gives an octahedral complex $Y$ in the presence of air. In aqueous solution,complex $Y$ behaves as a $1:3$ electrolyte. The reaction of $X$ with excess $HCl$ at room temperature results in the formation of a blue coloured complex $Z$. The calculated spin-only magnetic moment of $X$ and $Z$ is $3.87 \ B.M.$,whereas it is zero for complex $Y$.
Among the following options,which statement$(s)$ is(are) correct?
$[A]$ The hybridization of the central metal ion in $Y$ is $d^2sp^3$
$[B]$ $Z$ is a tetrahedral complex
$[C]$ Addition of silver nitrate to $Y$ gives only two equivalents of silver chloride
$[D]$ When $X$ and $Z$ are in equilibrium at $0^{\circ}C$,the colour of the solution is pink

The $d$-electronic configuration of an octahedral $Co(II)$ complex having magnetic moment of $3.95 \ BM$ is :

$A$ complex involving $dsp^2$ hybridization has:

Which of the following species have a square planar geometry for the central atom?
$(i) XeF_4 \ (ii) SF_4 \ (iii) [NiCl_4]^{2-} \ (iv) [PtCl_4]^{2-}$

The structure of $K[PtCl_3(C_2H_4)]$ and hybridization of $Pt$ respectively are: