Question

The Tyndall effect is not observed in:
A.Suspensions
B.Emulsions
C.Colloidal solutions
D.True solutions

Answer 1

Hint:We can define the Tyndall effect as the phenomenon of scattering of particles of light in its path. When a beam of sunlight enters into the dusty window through the window, then its path becomes visible to us.

Complete step by step answer:
We have to know the effect of light scattering in colloidal dispersion, while showing no light in a true solution is the Tyndall effect. This effect is used to determine if a mixture is a true solution or a colloid.
When we pass light through a true solution, the light passes through the solution, whereas when we pass light through a colloidal solution, the substance that is present in the dispersed phases scatters the light in all directions, making it readily visible.
Suspensions contain larger particles than colloids and that’s why they exhibit the Tyndall effect. Therefore, Option (A) is incorrect.
We can define an emulsion as a colloidal dispersion of a liquid in either a liquid or a solid. A stable emulsion requires the presence of an emulsifying agent. The particle sizes are larger in the solution of emulsion, hence they show Tyndall effect. Therefore, Option (B) is incorrect.
In colloidal systems the size of the particles present in dispersed-phase ranges from 1 to 200 nm. Because of the larger particle size, the colloid systems exhibit Tyndall's effect. Therefore, Option (C) is incorrect.
We can say a true solution is a homogeneous solution where the particles of solute contain diameters in the range of 0.1nm to 1nm. Size of the particles is very small, and is lesser than the colloidal range. Thus, true solutions do not show Tyndall effect as the particle is not large enough to scatter the light incident on it.
Therefore, Option (D) is correct./b>

Note:
When we pass light through water and milk. The light is not reflected when passing through the water as water is not a colloid. It is however reflected in all directions when it is passed through the milk that is colloidal. A second example is shining a flashlight into fog or smog; the beam of light could easily be visible because the fog is a colloid.