If cyclobutane were flat, it would have exactly 90° C-C-C bond angles and could conceivably use pure p orbitals in its C-C bonds. What would be a possible hybridization for the carbon atoms of the molecule that would allow all the C-H bonds to be equivalent? Exactly where would the hydrogen's on each carbon be located? What are the real structural features of the cyclobutane molecule that contradict this hypothesis?