Four metals were kept in contact with each other. The table below shows the initial temperature of the metals. Metal Initial Temperature
А
30 °C
B
42 °C
С
25 °C
D
16°C
From which metal will heat flow into all the other metals?
Metal A
Metal B
Metal C
Metal D

answer: the rate of diffusion increases with increase in temperature.

increase in temperature, increases the molecular/particles speed (kinetic energy. diffusion means movement of particles through the material.

generally, the heavier the particle the more it interacts with the environment and more the temperature matters. so higher temperature results in higher diffusion.

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).