Water is composed of hydrogen and which other element?

Water is a chemical compound made up of two hydrogen atoms and one oxygen atom, giving it the chemical formula H₂O. The presence of oxygen is crucial as it not only forms bonds with hydrogen to create water but also contributes significantly to water's unique properties, such as its solvent capabilities, high specific heat, and its vital role in biological systems.

Understanding the composition of water is fundamental in various fields, including esthetics, as it plays a critical role in skin hydration and overall health. Each of the other elements listed—carbon, nitrogen, and additional hydrogen—does not form water or any similar structure, making oxygen the sole correct answer in this context.