To identify a colloid mixture from a solution, you can use the Tyndall effect. This is where you pass a light through the mixture. If the light bounces off the particles, you will see the light shine through and you have a colloid mixture.
The Tyndall Effect is the effect of light scattering in colloidal dispersion, while showing no light in a true solution. This effect is used to determine whether a mixture is a true solution or a colloid.
