Answer
$N_2O_4$
Work Step by Step
In order to write the chemical formula for dinitrogen tetroxide, look at the prefixes. In front of the nitrogen there is a "di," which is the prefix for two. Thus, there are two nitrogens. The prefix for tetroxide is tetra, which means "4." This means that there are 4 oxygen atoms. The chemical formula for dinitrogen tetroxide is $N_2O_4$