What is the chemical formula of water?

The chemical formula of water is represented as H2O, which indicates that each molecule consists of two hydrogen atoms covalently bonded to one oxygen atom. This simple but essential compound is critical for life and plays a vital role in various biological, chemical, and physical processes. The arrangement of hydrogen and oxygen within the molecule contributes to water's unique properties, such as its high specific heat, surface tension, and solvent capabilities, making it a prime candidate for sustaining life on Earth. In contrast, the other options represent entirely different compounds: O2 refers to molecular oxygen, CO2 is carbon dioxide, and NaCl is sodium chloride. Each of these substances has distinct characteristics and applications, none of which relate to the molecular structure of water.