Question

How is Brownian motion caused?
(A) Through temperature fluctuations within the liquid phase
(B) Through attraction and repulsion between the charged on the colloidal particles
(C) Through collision of molecules between the colloidal particles
(D) Through pressure variations within the liquid phase

Answer 1

Hint: The Brownian motion can be explained as the movement of the particles at microscopic level and this type of movement generally depicts the random fluctuation in position inside a fluid subdomain. Also, the motion is unpredictable and is zigzag in nature.

Complete step by step solution:
- Let’s see in detail about Brownian motion. It refers to the random movement displayed by small or microscopic particles which are suspended in fluids and is generally referred to as Brownian movement.
-The Brownian motion is a consequence of the collisions of the particles with other fast-moving particles in the fluid. Or in other words, this type of movement is observed due to the collision between the particles inside a fluid domain.
-The Brownian movement is reliant on the temperature, size and number of particles and viscosity of the fluid medium. The rate of Brownian movement will increase as we increase the temperature, increase the number of particles etc. since all this will lead to higher frequency of collision of particles.
- In the case of colloids, the reason for the Brownian movement is the unbalanced bombardment or the collision between the colloidal particle and the dispersion medium. This movement will help to stabilize the colloidal solution since this Brownian motion does not allow the particles of the solution to settle down.
- From the above discussions it’s clear that the Brownian motion is caused through the collision of molecules between the colloidal particles,

Therefore the correct option is (C).

Note: The most common examples of Brownian motion include the dispersal of pollutants in the air, movement of pollen grains on still water, dispersal of calcium over the bones etc. Also, it should be noted that a true solution can be distinguished from a colloidal solution with the help of Brownian motion.