What are two things that you observed when you heated the mixture of tin and nitric acid over the bunsen burner in the virtual lab, and why was it necessary to heat the mixture in order to determine the empirical formula?

Sn + 4 HNO₃ →  SnO₂ + 4 NO₂ + 2 H₂O

Heating was required to get rid of the H₂O. When all moisture is gone, you weigh the sample. After which, you further heat it to get ride of the oxygen. By doing this, you would know the individual mass of each element. Then, you can solve for the empirical formula of the oxide of tin.

Hope this helps best of luck :)

Ibelieve its a because an empirical formula usually has a ch in it your options are a or b