Which of the following must be true for heat to flow from one substance to another? a. one oneonta the substance must always be a solid. b . one of the substance must always be a liquid. c. the substance must be at the same temperature d. the substance must be at different temperature

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.