What is the correct formula for sulfur dioxide?

The correct formula for sulfur dioxide is indeed SO2. This compound consists of one sulfur atom and two oxygen atoms. When we name the compound, the prefix "di-" indicates the presence of two oxygen atoms linked to the sulfur atom.

In this compound, sulfur has a valence of 6 and can form two double bonds with two oxygen atoms, creating a stable molecule. The name "sulfur dioxide" reflects this structure, as it denotes the specific ratio of sulfur to oxygen.

The formula SO would indicate only one oxygen atom, making it insufficient for naming the compound correctly. Meanwhile, SO3 represents sulfur trioxide, which has three oxygen atoms and a different name, while SO4 suggests a hypothetical compound that isn't correctly representative of sulfur dioxide. Thus, the choice of SO2 accurately captures the composition of sulfur dioxide, confirming its status as the correct formula.