Question

Identify the incorrect statement:

• A. Values of colligative properties of colloidal solutions are of small order compared to values of true solutions.
• B. Tyndall effect is observed only when the diameter of the dispersed particles is not much smaller than the wavelength of incident light.
• C. Colour of colloidal solution depends on the wavelength of light scattered by the dispersed particles.
• D. Brownian movement is due to balanced bombardment of molecules of the dispersion medium on colloidal particles.

Hint:

Brownian movement arises from random molecular collisions.

Answer 1

The Correct Option is D

To identify the incorrect statement among the given options, we need to understand several concepts related to colloidal solutions:

1. Colligative Properties: Colligative properties depend on the number of particles in a solution. In colloidal solutions, the number of dispersed particles is relatively less compared to true solutions, which generally have smaller particles but in larger numbers. Therefore, the values of colligative properties for colloidal solutions are indeed smaller than those for true solutions. Thus, this statement is correct.
2. Tyndall Effect: This phenomenon describes the scattering of light by particles in a colloid. It is observed only when the size of the dispersed particles is similar to or larger than the wavelength of incident light. Hence, this statement is also correct.
3. Colour of Colloidal Solution: The colour of a colloidal solution is indeed dependent on the wavelength of light that is scattered by the dispersed particles. This affects how we perceive the colour; hence, this statement is correct.
4. Brownian Movement: Brownian movement is the erratic random movement of colloidal particles. It occurs due to the bombardment of molecules in the dispersion medium on colloidal particles, but this bombardment is not balanced; it is random and from all directions, which is why the particles move randomly. The statement suggests that it is due to balanced bombardment, which is inaccurate.

Based on the explanations above, the incorrect statement is: Brownian movement is due to balanced bombardment of molecules of the dispersion medium on colloidal particles. The movement is actually due to unbalanced, random bombardment, not balanced.