What is the molecular formula for water?

The molecular formula for water is H2O, which indicates that each molecule of water is composed of two hydrogen atoms bonded to one oxygen atom. This formula is essential in chemistry as it illustrates the composition of water, a vital substance for all known forms of life. The two hydrogen atoms contribute to water's unique properties, such as its polarity, high specific heat, and ability to dissolve many substances, making it an excellent solvent.

In contrast, the other options represent different substances. CO2 is the formula for carbon dioxide, which consists of one carbon atom and two oxygen atoms; this gas is produced during respiration and combustion. O2H does not represent a valid molecular formula as it incorrectly implies an arrangement that does not exist chemically. Lastly, H2O2 is the molecular formula for hydrogen peroxide, consisting of two hydrogen atoms and two oxygen atoms; it is commonly used as a bleaching agent and antiseptic, rather than a component of water. Understanding these distinctions is crucial when studying chemical compounds, especially in the context of water's role in biological and environmental processes.