What is the molecular formula for water?

Water is a chemical compound composed of two hydrogen atoms covalently bonded to one oxygen atom. The molecular formula for water is written as H₂O, where the "2" indicates that there are two hydrogen atoms for every one oxygen atom. This formula succinctly represents the specific ratio of elements in the molecule, highlighting its molecular composition.

In contrast, the other choices represent different compounds. CO₂ denotes carbon dioxide, which consists of one carbon atom and two oxygen atoms. NaCl is the formula for sodium chloride, commonly known as table salt, made up of one sodium atom and one chlorine atom. CH₄, or methane, is a compound with one carbon atom and four hydrogen atoms. Each of these does not describe the composition of water, reinforcing that H₂O is the correct representation for this essential molecule.