The outer core is composed mainly of which two elements?

The outer core is composed mainly of which two elements?

• A. Iron and copper
• B. Nickel and zinc
• C. Silicon and oxygen
• D. Iron and nickel

Answer: (D)

The outer core is a molten, metallic layer, and its composition is dominated by iron with a significant amount of nickel. Iron is the most abundant heavy element in Earth’s core, and nickel is the next most common; together they form a liquid iron–nickel alloy at the extremely high temperatures present there. This liquid metal conducts electricity, and its convection helps generate Earth’s magnetic field. In contrast, silicon and oxygen are major components of rocks in the crust and mantle, not the metallic core, and copper or zinc aren’t known to be major core constituents. So iron and nickel best describe the outer core’s composition.

The outer core is a molten, metallic layer, and its composition is dominated by iron with a significant amount of nickel. Iron is the most abundant heavy element in Earth’s core, and nickel is the next most common; together they form a liquid iron–nickel alloy at the extremely high temperatures present there. This liquid metal conducts electricity, and its convection helps generate Earth’s magnetic field. In contrast, silicon and oxygen are major components of rocks in the crust and mantle, not the metallic core, and copper or zinc aren’t known to be major core constituents. So iron and nickel best describe the outer core’s composition.