Classification Of Colloids

The Tyndall effect is the scattering of light by particles in a colloid or in very fine suspensions. Solutions that exhibit the Tyndall effect appear colorful when viewed from a direction perpendicular to the light beam due to the scattering of light. Let's analyze the options to identify which solution shows this effect:

1. NaCl solution: Sodium chloride forms a true solution when dissolved in water, which means the particles are completely dissociated into ions. True solutions do not scatter light because their particles are too small to scatter visible light, so they do not exhibit the Tyndall effect.
2. Glucose solution: Glucose, like NaCl, forms a true solution in water. The particles or molecules of glucose are also too small to scatter light, hence, it does not show the Tyndall effect.
3. Starch solution: Starch forms a colloidal solution in water. Colloids have larger particle sizes compared to true solutions, which can scatter light and thus exhibit the Tyndall effect. This scattering is what makes the beam of light visible in the colloidal dispersion of starch in water.
4. Urea solution: Similar to NaCl and glucose, urea dissolves in water to form a true solution. Particles are too small to scatter light, so it does not show the Tyndall effect.

Based on the above analysis, the correct answer is the starch solution because starch forms colloidal particles that are capable of scattering light, displaying the Tyndall effect.

Conclusion: The right option for the statement "Tyndall effect is exhibited by" is the starch solution, as it is the only one that forms a colloid. The particle sizes in colloids are large enough to affect the passage of light through them, leading to light scattering.

Tip: Remember, the Tyndall effect is a characteristic of colloids and not of true solutions.