Question

Which of the following will show “Tyndall effect”?

• A. Salt solution
• B. Milk
• C. Copper sulphate solution
• D. Starch solution

Answer 1

The Correct Option is B, D

The Tyndall effect is the scattering of light by particles in a colloid or in very fine suspensions. When a beam of light passes through a colloid, the particles in the colloid scatter the light, making the beam visible. This is known as the Tyndall effect. Let's analyze each option to identify which solutions will show the Tyndall effect: 

1. Salt Solution: A salt solution is a true solution where salt is completely dissolved in water, forming ions at the molecular level. It does not scatter light as the particle size is too small. Therefore, it does not show the Tyndall effect.
2. Milk: Milk is a colloid, specifically an emulsion, in which fat droplets are dispersed in water. The particles in milk are large enough to scatter light, so milk does exhibit the Tyndall effect.
3. Copper Sulphate Solution: Similar to the salt solution, copper sulphate dissolves completely, forming a true solution with particles at the ionic level. It does not scatter light and thus does not show the Tyndall effect.
4. Starch Solution: Starch solution is a colloidal solution, where starch molecules are dispersed uniformly in water. The size of the starch particles is large enough to scatter light, thereby exhibiting the Tyndall effect.

Given the above analysis, the correct answers are Milk and Starch solution as both will show the Tyndall effect due to their colloidal nature.