Why is nitrogen gas (N₂) a gas at room temperature?

Nitrogen gas (N₂) exists as a gas at room temperature primarily due to the presence of weak intermolecular forces, specifically Van der Waals forces, between its molecules. These weak forces arise from the nonpolar nature of the nitrogen molecules, which consist of two nitrogen atoms bonded together by a triple covalent bond. As a result, the attractive forces between the nitrogen molecules are not strong enough to hold them together in a liquid or solid state under standard conditions.

Because these intermolecular forces are relatively weak, they require little energy to overcome, allowing nitrogen gas to remain in the gaseous state at room temperature. This characteristic is typical of many diatomic gases composed of nonpolar molecules.

The other choices do not accurately describe the behavior of nitrogen gas at room temperature. For example, a complex molecular structure would generally lead to stronger intermolecular forces, potentially resulting in a solid or liquid state. Ionic bonds, on the other hand, are typically found in compounds with more stable structures like salts, and are not applicable to diatomic nitrogen. Finally, although nitrogen is a relatively unreactive gas, its reactivity alone does not explain its gaseous state under normal conditions.