$Cu^{2+}$ shows a coordination number of

Which of the following has $dsp^2$ hybridization?

Among $Ni(CO)_4, [Ni(CN)_4]^{2-}$ and $[NiCl_4]^{2-}$,which of the following statements is correct?

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

Which of the following is correctly matched?

Consider the following test for a group-$IV$ cation.
$M^{2+} + H_2S \rightarrow A$ (Black precipitate) $+$ byproduct
$A + \text{aqua regia} \rightarrow B + NOCl + S + H_2O$
$B + KNO_2 + CH_3COOH \rightarrow C + \text{byproduct}$
The spin only magnetic moment value of the metal complex $C$ is $BM$. (Nearest integer)