Which of the following is the most dense part of the Earth?

The core is the most dense part of the Earth due to its composition and the conditions it experiences. It is primarily composed of iron and nickel, which are among the heaviest elements. The central core is under immense pressure and reaches extremely high temperatures, leading to a solid inner core surrounded by a liquid outer core. This combination of heavy metals and high pressure results in a density that significantly exceeds that of the crust, mantle, and atmosphere.

In contrast, the crust is the outermost layer and consists mainly of lighter minerals, making it the least dense. The mantle lies beneath the crust and, while it is denser than the crust, it is still not as dense as the core. The atmosphere, being a layer of gases, has the lowest density of all Earth's layers. Thus, the core's unique composition and extreme conditions contribute to it being the most dense part of the Earth.