Multiple choice The core of the earth is thought to be composed of Radioactive metals Molten metallic sulphides Molten iron and nickel Molten copper and iron Reveal answer Fill a bubble to check yourself C Correct answer Explanation The inner core of the Earth, its innermost hottest part as detected by seismological studies, is a primarily solid ball. It is believed to consist of an iron-nickel alloy, and may have a temperature similar to the Sun's surface.