What element is the primary component of molecular clouds?

Hydrogen is the primary component of molecular clouds due to its overwhelming abundance in the universe. These clouds, also known as stellar nurseries, are regions where gravitational collapse can lead to star formation. While hydrogen exists in atomic and ionized forms in various environments, molecular clouds contain hydrogen in molecular form (H₂), which is necessary for cooling the cloud to facilitate gravitational collapse. Other elements like helium, carbon, and oxygen are present in trace amounts, but hydrogen dominates due to its low atomic mass and ability to form stable molecular bonds in these cold environments.