Water is classified as a compound. A compound is a substance formed when two or more chemical elements are chemically bonded together. In the case of water, it is made up of two hydrogen atoms and one oxygen atom, chemically bonded to form H2O.
Water is not an element because it is not made up of only one type of atom. Elements are pure substances that consist of only one type of atom, such as oxygen (O) or hydrogen (H).
Water is also not a mixture. A mixture is a combination of two or more substances that are not chemically bonded. Mixtures can be separated into their individual components by physical means, such as filtration or evaporation. Since water is a compound, it cannot be separated into hydrogen and oxygen by physical means; it requires a chemical reaction.
Lastly, water is considered a pure substance when it is in its pure form, meaning it contains only H2O molecules without any impurities. However, in everyday usage, water often contains dissolved minerals and gases, making it a mixture rather than a pure substance.