Final answer:
Hydrogen occurs mainly in combination with oxygen and water, as well as in organic matter such as living plants, coal, and petroleum.
Step-by-step explanation:
True. Hydrogen occurs mainly in combination with oxygen and water, as well as in organic matter such as living plants, coal, and petroleum. Water, which contains hydrogen and oxygen, is essential to all living processes and is the most abundant compound of hydrogen found on Earth. Hydrogen is also an important component of petroleum, cellulose, starch, sugar, fats, oils, and many other substances.