Question

Why liquid diffuse slowly as compared to gases?

Answer 1

Because of the arrangement of the atoms
In the solids the molecules are tightly packed , where as in gases molecules are loosely packed .and that the reason for diffusion .Diffusion is far different from OSMOSIS..

Answer 2

Liquids diffuse slowly because in liquids molecules are less free compared to gas, so vanderwaals forces are higher and that's why gases diffuses faster.