How much hydrogen is composed in a nebula?

Nebulae are primarily composed of hydrogen, which can make up about 70-90% of their mass, depending on the specific type of nebula. In regions of star formation, the hydrogen is often in its atomic form (H I) or molecular form (H₂). The remaining composition typically includes helium, dust, and trace amounts of heavier elements. The exact percentages can vary based on the nebula's location and evolutionary stage.