Question

"Tyndall effect" will be shown by which of the following ?

• A. Distilled water
• B. Sugar solution
• C. Ethanol
• D. Starch solution

Hint:

The Tyndall effect is a key characteristic distinguishing colloids and fine suspensions from true solutions. If you can see the light beam passing through a transparent liquid, it's likely a colloid.

Answer 1

The Correct Option is D

Step 1: Understand the Tyndall effect.
The Tyndall effect is the phenomenon where light is scattered by particles in a colloid or a fine suspension, making the path of the light visible. This effect is observed when the dispersed particles are large enough to scatter light, but small enough that they do not settle out of the dispersion. True solutions (like distilled water, sugar solution, and ethanol) have particles that are too small to scatter light effectively, so they do not show the Tyndall effect. Step 2: Classify the given options based on particle size.
Distilled water: A pure substance, essentially a true solution, with particles too small to scatter light.
Sugar solution: A true solution where sugar molecules are dissolved in water; their size is too small to cause significant scattering.
Ethanol: A pure substance, or if considered in solution with water, forms a true solution. Particles are too small.
Starch solution: Starch in water forms a colloidal dispersion (or a fine suspension, depending on concentration and preparation). The starch particles are large enough to scatter light. Step 3: Determine which solution will exhibit the Tyndall effect. Based on the principle that only colloids and fine suspensions exhibit the Tyndall effect, starch solution is the correct answer because it forms a colloidal dispersion. $$(4) Starch solution$$