Storng Tyndall effect is observed only when
(i) the refractive indices of the dispersed phase and the dispersion medium differ greatly in magnitude
(ii) the diameter of the dispersed particles is biggest than the wavelength of the light used
(iii) the refractive indices of the dispersed phase and the dispersion medium are similar
(iv) the diameter of the dispersed particles is not much smaller than the wavelength of the light used.

Options

A. `(i),(ii)`
B. `(i),(iv)`
C. `(iii),(iv)`
D. `(ii),(iii)`

Answer

B

Explanation

The intensity of the scattered light is directly proportional to the difference between the refractive indices of the dispered phase and the disperison medium. In lyophobic sols, the Tyndall effect is strong because this difference is appreciable on account of weak or no intraction between the two phases. While in lypophilic sols the Tyndall effect is much weaker because the particles are largely solvated which lowers the difference in the refractive indices of the two phases. For effective scattering of light, the diameter of the particles should match with the wavelength of the light.