Question

Suspension shows Tyndall effect because of:
A) large size of particles.
B) small size of particles.
C) their settling down nature.
D) none of the above.

Answer 1

Hint: We know that Tyndall effect is nothing but the scattering of the light by particles floating in the air or in the solution. We know that particle size is important to define such types of effects. The solution suspension and colloid differ due to their particle size.

Complete answer:
> When light passes through medium it gets refracted, reflected and absorbed. The light passes through the medium and gets scattered because of its particles after getting incident on the particles. The size of the particles will scatter the light in different ways, the size of the particles in the suspension are larger so that it will scatter the light and we can see the path of light as it travels through the solution.
> If the size of the particles in the solution is small, then we cannot see the scattering of light. True solution does not show Tyndall effect because particles of solute dissolve in the solvent is very small the light does not get scattered by such small size particles. Tyndall effect can be seen in the forest or in a dark room from which the light ray is coming. The particles scatter the light ray and we can see each particle floating in that beam of light.

Hence, the answer is (A) the large size particles.

Note: There are three types of solution as we know out of three, colloid and few suspensions show such property of scatter of incident light because of particles size that is its diameter is in between \[40 - 900\] nm. Different wavelengths of light scatter differently. Hence, we can say that the wavelength and size both play a role in Tyndall effect to happen.