<span><u>Answer</u>
c). random internal motion of atoms and molecules.
<u>Explanation </u>
Diffusion is the movement of particles from a region of high concentration to region of low concentration. The rate of diffusion can be increased by increasing amount of temperature but this is not its primary cause. Diffusion is primarily caused by movement of molecules or atoms in a substances. Form the choices given, the correct answer is c. random internal motion of atoms and molecules.
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The answer is 9.8 ms^-2, because there is only one force acting on the object so the acceleration will be numerically equal to the gravitational field strength.
<span>a decrease in the distance between the earth and the moon</span>
