In the extraction of silver,zinc metal is used as a reducing agent. What is the molecular structure of the zinc complex formed in this reaction?

In an octahedral geometry,which pair of $d$-orbitals is involved in $d^2sp^3$ hybridization?

Reaction of $[Co(H_2O)_6]^{2+}$ with excess ammonia and in the presence of oxygen results into a diamagnetic product. Number of electrons present in $t_{2g}$-orbitals of the product is $.....$ .

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 hybridisation and unpaired electrons in $[Fe(H_2O)_6]^{2+}$ ion are:

Which statement is incorrect?