Hydrogen's normal phase at standard temperature and pressure (STP) is gaseous.

Here's why:

* Low boiling point: Hydrogen has a very low boiling point of -252.87 °C (-423.17 °F). This means it readily transitions into a gas at even slightly above this temperature.

* Weak intermolecular forces: Hydrogen molecules are very small and have weak intermolecular forces (London dispersion forces). This makes it difficult for them to stay together in a liquid or solid phase.

Therefore, under normal conditions, hydrogen exists as a colorless, odorless, and highly flammable gas.