Question

The zig-zag random motion of colloidal particles in a dispersion medium is called:
A) brownian motion
B) tyndall effect
C) electrophoresis
D) electro-osmosis

Answer 1

Hint: Colloidal is a mix in which one or more substances are dispersed as relative like large solid particles or liquid droplets throughout a solid, liquid, or gaseous medium. The particles of a colloid remain dispersed and not get settled due to the effect of gravity, and they are electrically charged too.

Complete answer:
> Brownian motion is the zig-zag motion of colloidal particles in a dispersion medium.
> Tyndall effect is the phenomenon of scattering of light because of colloidal particles.
> Electrophoresis is a technique used in laboratories in order to separate macromolecules based on size.
> Electro-osmosis is the motion of liquid induced by an applied potential over the porous material, capillary tube, membrane or any other fluid body.
> Colloidal particles are constantly bombarded through the molecules of the dispersion medium on all sides. The effects are not the same every time in the direction. As a result, the sol particles basically show random or zig-zag movements. This random or zig-zag movement of the colloidal particles in a sol is defined as Brownian movement or Brownian motion.
> The Brownian movement will become step by step much less prominent, because the particles will grow in size or the viscosity of the medium will increase.

Therefore the correct answer is option A. brownian motion.

Note: The phenomenon of Brownian movement was first found by Robert Brown in the shape of random zig-zag movement of pollen grains in the water. This type of motion is determined in all types of colloidal systems. Such random movement is seen below ultramicroscopes and for larger particles even below simple types of microscopes.