What is the correct formula for sulfur dioxide?

The correct formula for sulfur dioxide is SO2, which indicates that each molecule consists of one sulfur atom and two oxygen atoms.

In the name "sulfur dioxide," the prefix "di-" is derived from Greek, meaning "two," which directly corresponds to the two oxygen atoms present in the compound. When naming molecular compounds, the number of atoms of each element is denoted by prefixes, which helps to distinguish between compounds that may contain the same elements but in different ratios.

For comparison, the other formulas represent different compounds with varying numbers of oxygen atoms. For instance, SO corresponds to sulfur monoxide, SO3 represents sulfur trioxide, which has three oxygen atoms, and SO4 would imply a hypothetical compound that is not commonly recognized or used in chemical nomenclature. Such distinctions are important to understand in order to accurately name and write the formulas for chemical compounds.