Question

Tyndall effect is observed in which one of the following ?
a) True solution
b). starch + water
c) Alum + water
d) NaCl+water​

Answer 1

Tyndall effect is observed in b). starch + water.

• Tyndall effect will be observed in colloidal solutions. Particles remain in suspension in colloidal solutions while a true solution is a homogenous mixture where particles cannot be observed by the naked eye.
• In colloidal solutions, the particle size ranges from 1 nanometre to 1 micrometre. The size of the particles is large enough to scatter the incoming beam of light, which is why the Tyndall effect is caused.
• True solution cannot cause the Tyndall effect as the particle size is too small to scatter the beam of light. The particle size is less than 1 nanometre in true solutions.
• Alum water and NaCl+water will form true solutions. While starch+water is a colloidal solution.