Question

Which of the following will show “tyndall effect”?
This question has multiple correct options
A. Salt solution
B. Milk
C. Copper sulphate solution
D. Starch solution

Answer 1

Hint: .We can say that the tyndall effect can be used to verify if a given solution is a colloid. This effect is shown by all the colloidal solutions and by some very fine suspensions. Find out which among the given options are colloidal solutions and that should be your answer.

Complete answer: - Let’s see the Tyndall effect phenomenon: it is a process in which the particles in a colloid scatter the beams of light that are directed towards them.
- It is very important that the intensity of scattered light depends on the density of the colloidal particles as well as on the frequency of the incident light.
- When a beam of light is passed through a colloid, then the colloidal particles that are present in the solution do not allow the beam to completely pass through. The light collides with the colloidal particles and then it is scattered (that is it deviates from its normal path, which is a straight line). This scattering makes the path of the light beam visible.
-The scattering of light by colloidal solution tells us that the colloidal particles are much bigger than the particles of a true solution.
- We can see that the correct options are (B) and (D), milk and starch solution are the colloids, hence these will show the tyndall effect.
So, the correct answer is “Option B and D”.

Additional Information: - Generally, blue light is scattered to a larger extent as compared to red light. This is because the wavelength of blue light is smaller than that of the red light. This is the reason why we can see the smoke released by motorcycles sometimes appears blue.
- The Tyndall effect was first discovered by John Tyndall.

Note: - The tyndall effect shows that the colloidal particles are much bigger than the particles of a true solution and smaller than particles in suspensions. The colloids are also identified by their random movements through the fluid which is known as the brownian movement.