Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which material is the Earth's core predominantly composed of?

1. Aluminum

2. Iron

3. Oxygen

4. Carbon

The correct answer is: Iron

The Earth's core is predominantly composed of iron. This conclusion is supported by various geological and seismological studies that have analyzed the properties of seismic waves as they travel through the Earth. The inner core is solid and primarily consists of iron, while the outer core is liquid and also mainly made up of iron, along with some nickel and lighter elements. The high density and gravitational force at the Earth's center lead to the accumulation of heavy elements like iron, which play a crucial role in the generation of the Earth's magnetic field through the dynamo effect. Understanding the composition of the core is essential in geophysics, as it provides insights into planetary formation and the dynamics of Earth’s interior. In contrast, the other materials listed – aluminum, oxygen, and carbon – are either abundant in the Earth's crust or atmosphere but do not significantly contribute to the core's overall composition.