Question

why colloids show tyndall effect not true solutions

Answer 1

in the true solution the solute is dissolved completely and the particle size is less than 1nm which is not big enough to scatter light ie,show tyndall effect but in the colloidal solution the particles are big enough to scatter a beam of light and thus show tyndall effect.

Answer 2

Tyndall effect refers to the scattering of light by colloidal particles.

The intensity of the scattered light depends on the difference in the refractive indices of the dispersed phase and the dispersion medium. Larger the difference, greater will be the intensity of the scattered light.

In lyophobic sols, the particles are not as highly solvated as in lyophilic sols. So, the difference in refractive indices between the particles and the medium is quite large in lyophobic sols. Therefore, they show distinct Tyndall effect.