I was looking at the chemical structure of H₂SO₄ from http://www.webanswers.com/education/high-school/what-is-the-chemical-symbol-of-sulfuric-acid-23fae0.

Intuitively, I would have expected this molecule to be square planar in a p²d² or sp²d geometry but rather, it is shown to be in an tetrahedral geometry in an sd³ geometry.

I guess that an alternative way of asking this question is what is the hybridization of H₂SO₄?