Question

The rate of diffusion of molecules is proportional to kinetic energy,size ??

Answer 1

well diffusion is the process by which particles move from the region of higher concentration to the lower one. thus, in order to achieve this objective kinetic energy plays an important role.

Answer 2

kinetic energy is the right answer.
Size won't affect the rate of diffusion but higher kinetic energy of the particles will make the diffusion faster.