What is the chemical formula for water?

• A. H2O
• B. CO2
• C. O2
• D. NaCl

Answer: (A)

The chemical formula for water is represented as H2O. This indicates that each molecule of water contains two hydrogen atoms (H) bonded to one oxygen atom (O). The combination of these elements is essential for the formation of water, which is a critical substance for all forms of life.

Water's unique properties, such as its solvent capabilities and its role in biochemical reactions, stem from its molecular structure and the polar nature of the hydrogen-oxygen bonds. This formula is fundamental in chemistry and biology, as it outlines not only the composition of water itself but also provides insight into various environmental and physiological processes involving water.

Understanding that the chemical formula encapsulates the ratio of the constituent elements is crucial. The other options represent different compounds: carbon dioxide (CO2) is comprised of carbon and oxygen; oxygen gas (O2) consists of two oxygen atoms; and sodium chloride (NaCl) is a compound made of sodium and chlorine. Each of these serves different functions and is important in their respective contexts, but only H2O signifies water.