During an experiment the students prepared three mixtures A)Starch in water B) Sodium chloride solution C) Tincture of Iodine. i) Students observed a visible beam of light through mixture A. Why? ii) Tincture of Iodine did not show Tyndall effect . Explain reason. iii) How can you relate particle size to Tyndall effect?

The question requires a good knowledge of the meaning of Tyndall effect or scattering of light by false solutions in chemistry

The student observed a beam of visible light through mixture A because A exhibits Tyndall effect

Tincture of Iodine does not show Tyndall effect because its solution consists of particles less than 1 nanometer in solution.

A solution may be classified as a true solution or a false solution. A true solution consists of particles which are less than 1 nanometer in solution. A true solution does not scatter visible light.

A false solution, on the other hand consists of particles larger than 1 nanometer and does scatter visible light.

Starch in water is an example of a false solution or colloid hence it exhibits Tyndall effect. The scattering of visible light by a solution is known as Tyndall effect.

Tincture of iodine and sodium chloride in water are all true solutions hence they do not scatter visible light.

since electrons are negative the answer is neagtaive