Final answer:
Pure hydrogen is not commonly found on Earth in its elemental form. It is mainly present in water and organic compounds. While it can be obtained from water through electrolysis, it is not commercially viable. Hydrogen is the most abundant element in the universe and plays a crucial role in stars and fusion reactions.
Step-by-step explanation:
On Earth, pure hydrogen is not found abundantly in its elemental form. The most common form of hydrogen on our planet is as water (H₂O), where hydrogen is chemically bonded to oxygen. Hydrogen is also present in organic compounds like hydrocarbons. In the atmosphere, hydrogen is a trace gas with only 0.5 parts per million (ppm).
While pure hydrogen can be obtained from water through electrolysis, this method is not commercially viable due to the significant amount of energy it requires. Additionally, hydrogen gas is so light that it eventually diffused into space over time and is now absent from the Earth's atmosphere.