Question

why copper sulphate solution in water does not show tyndall effect but mixture of water and milk shows?​

Answer 1

copper sulphate crystals are highly soluble in water and they form a true solution in water. Their particles size is very small so they do not scattering beam of light and does not show Tyndall effect

Answer 2

copper sulphate soln. is a true solution and homogeneous.Water and milk are a colloid solution (emulsion).Tyndall effect is observed only in colloids as particles in solution are not large enough to diffuse light .