Science Olympiad Dynamic Planet Practice Test

What is the inner core of the Earth primarily composed of?

1. Granite and basalt

2. Solid iron and nickel

3. Liquid iron and sulfur

4. Rock and organic matter

The correct answer is: Solid iron and nickel

The inner core of the Earth is primarily composed of solid iron and nickel. This layer is the deepest part of the Earth's structure, located below the outer core, and is subjected to extremely high temperatures and pressures. The temperature in the inner core can reach up to 5,700 degrees Celsius (about 10,300 degrees Fahrenheit), which is comparable to the surface of the sun. Despite these high temperatures, the inner core remains solid due to the immense pressure from the layers above it, which prevents the iron and nickel from melting. This solid state of iron and nickel is a key feature of the inner core, contributing to the Earth's magnetic field through the dynamo effect, where the movement of the molten outer core generates electric currents. Understanding the composition of the inner core is vital to our knowledge of Earth's geodynamics and how its internal processes influence surface phenomena like plate tectonics and volcanic activity.