Final answer:
Oxygen is the most abundant element on Earth, making up about 21% of Earth's atmosphere. It is essential for most forms of life and is used by all living things to make molecules that are necessary for life.
Step-by-step explanation:
Oxygen is the most abundant element on Earth, making up about 21% of Earth's atmosphere.
It is essential for most forms of life and is used by all living things to make molecules that are necessary for life.
Oxygen is also a necessary reactant in the combustion process and dilutes nitrogen to prevent rapid burning at the Earth's surface.