I was looking at the chemical structure of H<sub>2</sub>SO<sub>4</sub> from http://www.webanswers.com/education/high-school/what-is-the-chemical-symbol-of-sulfuric-acid-23fae0.

![enter image description here][1]
![enter image description here][2]

Intuitively, I would have expected this molecule to be square planar in a p<sup>2</sup>d<sup>2</sup> or sp<sup>2</sup>d geometry but rather, it is shown to be in an tetrahedral geometry in an sd<sup>3</sup> geometry.

I guess that an alternative way of asking this question is what is the hybridization of H<sub>2</sub>SO<sub>4</sub>?

  [1]: https://i.sstatic.net/izuvo.png
  [2]: https://i.sstatic.net/c1Mup.jpg