Describe some of the most important element found on earth

IRON

The vast majority of the Earth's supply of iron is found in the core and the mantle. The solid inner core is almost entirely composed of iron, while the liquid outer core is an alloy of iron and nickel, with small amounts of lighter elements. The mantle is composed of iron-magnesium silicates, and the crust is composed of roughly 5 percent iron. All together, iron makes up an estimated 35 percent of the Earth's mass.

Oxygen

Oxygen, the second most abundant element on Earth, is found mainly in the crust. Although oxygen is most often thought of as an atmospheric gas, it is also one of the primary components of the silicate minerals that make up the vast majority of the Earth's crust. Oxygen itself makes up approximately 46.6 percent of the crust and 30 percent of the mass of the entire Earth.

carbon, hydrogen, nitrogen, oxygen

i need with 1.3.2 investigate cycling o2 and co2 apex

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answer a fan shaped mass of sediment deposited at the base of a mountain front do to an abrupt change in stream gradient;