The document defines key scientific terms including air, alloy, boiling point, chromatography, condenser, crude oil, and dissolve. It provides brief descriptions of each term, noting that air is a mixture of gases including nitrogen and oxygen, alloy is a mixture of metals, boiling point is the temperature at which a liquid changes to a gas such as water boiling at 100°C, and chromatography and dissolve involve the separation or mixing of substances.