Answer:
metals sunk to the centers a long time ago when the interiors were molten throughout
Explanation:
The cores of the terrestrial worlds are made mostly of metal because metals sunk to the centers a long time ago when the interiors were molten throughout.
In the history of the formation of the earth, it has been explained that billions of years ago during the formation of the earth, heavy materials such as metals sank into the middle of the developing planet while lighter materials stayed closer to the earths crust. Below the earth's crust is the mantle and the earth's core which is divided into the outer core and the inner core. The outer core is comprised mainly of combination of iron, nickel, platinum, gold and even uranium while the inner core is made of mainly solid iron.