Which of the following species/ions has an octahedral geometry?

As the $s$-character of a hybrid orbital increases,the bond angle

In $CH_4$ molecule,the hydrogen atoms around carbon are arranged as

Observe the following reactions. Identify the reaction in which the hybridisation of the underlined atom is changed.

What is the hybridization of the central atom in $SiF_6^{2-}$ and $[Sn(OH)_6]^{2-}$?

Among $[I_3]^{+}$,$[SiO_4]^{4-}$,$SO_2Cl_2$,$XeF_2$,$SF_4$,$ClF_3$,$Ni(CO)_4$,$XeO_2F_2$,$[PtCl_4]^{2-}$,$XeF_4$,and $SOCl_2$,the total number of species having $sp^3$ hybridised central atom is. . . . .