Here's why:
* Crust: The crust is the outermost layer, composed primarily of lighter elements like silicon, oxygen, and aluminum. Its density ranges from 2.7 to 3.0 g/cm³.
* Mantle: The mantle lies beneath the crust and is made up of denser rocks like peridotite. Its density ranges from 3.3 to 5.5 g/cm³.
* Outer Core: The outer core is a liquid layer composed mostly of iron and nickel. Its density is higher than the mantle, ranging from 9.9 to 12.2 g/cm³.
* Inner Core: The inner core is a solid sphere of iron and nickel, with the highest density of all layers, ranging from 12.6 to 13.0 g/cm³.
Therefore, the crust, being the outermost layer composed of lighter elements, has the lowest density.
