It is greater when the substance is at a higher temperature. This is because the mean square speed of the molecules of a system is proportional to thermodynamic temperature.
Diffusion.
Diffusion is a passive process, meaning that it requires no energy input from a cell or other source, other than the energy of motion that all substances have above absolute zero (0o...
Matter is made up of atoms and molecules (groupings of atoms) and these atoms and molecules are constantly jiggling around, bumping into each other. When the molecules (for example a water molecule...