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

Which of the following statements is incorrect regarding $[Ni(dmg)_2]$?

Which of the following is/are correct for the complex $[Cu(NH_3)_4]^{2+}$?

How many unpaired electrons are present in the cobalt ion in the $+3$ oxidation state prior to hybridization in the $[CoF_6]^{3-}$ complex ion?

For the coordination compound $[Co(NH_3)_5CO_3]ClO_4$,what are the coordination number,oxidation state,number of electrons in the $d$-orbitals,and the number of unpaired electrons for the central metal $Co$?

Which of the following statements are true about $[NiCl_4]^{2-}$?
$(a)$ The complex has tetrahedral geometry
$(b)$ Coordination number of $Ni$ is $2$ and oxidation state is $+4$
$(c)$ The complex is $sp^3$ hybridised
$(d)$ It is a high spin complex
$(e)$ The complex is paramagnetic