Identify the geometry of the complex ion if the hybridization is d2sp3. linear square planar octahedral trigonal planar tetrahedral

Octahedral   is  the  geometry  of the   complex   ion   which   has  d2sp3   hybridization.

 The  octahedral   has  eight   faces   hence  the  prefix  octa.    Octahedral  molecular   geometry   describe  the  shape  of  compound  with  six  atom   or  groups  of atoms  or  ligands  symmetrically  arranged  around  a  central  atom.The  octahedron   is one   of the  platonic  solids.

Yes, endothermic means it turns cold. and some chemical changes include change of tempature.