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Why does nitrogen boil before oxygen during the distillation of liquefied air?

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A labeled diagram of a periodic table entry for nitrogen shows its atomic number 7, symbol N, electron configuration, atomic weight, and name. Symbols indicate nitrogen is a nonmetal gas at room temperature, has a hexagonal crystal structure, and strongly acidic higher-valence oxides. A key explains the diagram's icons and color coding.
nitrogen

During the fractional distillation of liquefied air, nitrogen boils before oxygen because it has a lower boiling point.12

The boiling point of nitrogen is approximately āˆ’195.8 Ā°C (āˆ’320.4 Ā°F), which is about 13 Ā°C (23 Ā°F) lower than that of oxygen. In the process of distillation, the most volatile substanceā€”the one with the lowest boiling pointā€”vaporizes first, allowing for the separation of components based on their differing boiling temperatures. Consequently, as the liquefied air is heated, the nitrogen transitions into a gas and is separated, while the oxygen remains in the liquid state.12