Answer
A. $CaI_2$
B. $N_2O_4$
C. $SiO_2$
D. $ZnCl_2$
Work Step by Step
Write down the molecular formula designated by the type and number of atoms given. Make sure to place cations first and follow up with anions in order to get the correct formula. For B, the four oxygen atoms are bonded around the two central nitrogen atoms, so nitrogen goes first in the molecular formula.