Final answer:
The claim that "Water is not H2O" is false because water's unique properties, such as solvent capabilities and forming hydronium ions, are intrinsically linked to its molecular structure H2O as understood in chemistry.
Step-by-step explanation:
The statement "Water is not H2O" is false in all possible worlds because water is, in fact, chemically known as H2O which is a molecule consisting of two hydrogen atoms bonded to one oxygen atom. This unique molecular structure gives water its essential properties and allows it to exist as a liquid, solid, and gas within the conditions present on Earth. The special characteristics of water, such as its high surface tension, solvent abilities, and its role in chemical reactions like the formation of hydronium ions (H3O+), are all due to its molecular composition of H2O.
The historical philosopher Thales of Miletus theorized that water is the fundamental substance, which reflects the importance and unique nature of water in philosophical and scientific contexts. When considering modern science, hydrogen ions (protons) do not exist freely in water; they bond with H2O to form hydronium ions, further emphasizing that water's chemical identity is reliant on its composition as H2O. Water's ability to form H3O+, along with its other unique properties, confirms its chemical formula H2O and invalidates the claim that "Water is not H2O" in any world.