What is known as the "universal solvent" because it can dissolve a variety of different substances?

Water is referred to as the "universal solvent" due to its remarkable ability to dissolve more substances than any other liquid. This characteristic is primarily because of its polarity; water molecules have a slight positive charge on one side and a slight negative charge on the other. This polarity allows water to interact effectively with various chemical compounds, breaking them apart and integrating them into the solution.

Substances such as salts, sugars, acids, and even gases can dissolve in water, making it essential in biological systems, environmental processes, and industrial applications. The ability to facilitate reactions by dissolving solutes is a key reason why many life forms depend on water for survival.

While oxygen, solvent generally, and sodium chloride do have their own importance in different contexts, they do not match the solvent capabilities of water. Oxygen is primarily a gas critical for respiration, sodium chloride is a specific compound (table salt) that needs water for dissolution, but neither has the broad dissolving capacity that characterizes water.