What is the number of unpaired electrons present in $[CoF_6]^{3-}$?

Pick out the correct statement with respect to $[Mn(CN)_6]^{3-}.$

Cobalt chloride when dissolved in water forms a pink-colored complex $X$ which has an octahedral geometry. This solution,upon treatment with concentrated $HCl$,forms a deep blue complex $Y$ which has a $Z$ geometry. $X$,$Y$,and $Z$,respectively,are:

Hybridizations of the central atom in $[Fe(H_2O)_6]^{3+}$ and $[Co(NH_3)_6]^{3+}$,respectively,are

Hybridization in $[Ni(CO)_4]$ and $[Ni(CN)_4]^{2-}$ are respectively . . . . . . .

Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory:
$(i)$ $[Fe(CN)_6]^{4-}$
$(ii)$ $[FeF_6]^{3-}$
$(iii)$ $[Co(C_2O_4)_3]^{3-}$
$(iv)$ $[CoF_6]^{3-}$