Question

The hottest layer of the earth is the _____.

Answer 1

The correct answer is - inner core.

The Earth's inner core is the deepest layer of the Earth, and it practically represents the center of the Earth. It is a layer composed predominantly of iron-nickel alloy. In here we have the biggest temperatures and pressures, the temperature on the surface on the inner core is estimated to be like that of the Sun's surface, 5430 C degrees.  

Answer 2

The inner core is the hottest part because temps increase the deeper into earth.