Praxis Math and Science (5008) Practice Exam

The chemical formula for water is H₂O, which indicates that each molecule of water is composed of two hydrogen atoms and one oxygen atom. This simple yet crucial formula represents the unique structure of water, showcasing its molecular composition clearly. Water plays a vital role in various biological, chemical, and environmental processes, which makes its accurate representation through its chemical formula essential for understanding its function and behavior in different contexts.

In contrast, CO₂ denotes carbon dioxide, which consists of one carbon atom and two oxygen atoms. O₂ symbolizes molecular oxygen, essential for respiration and combustion, composed of 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. Each of these alternatives represents different compounds with distinct properties and roles in science.