Question

when a beam of light was passed through the solution of susbstance A dissolved in water, the path of light could be seen. what is this phenomenon called? what is the nature of the solution?

Answer 1

This phenomenon is called Tyndall effect. Tyndall effect is the phenomenon of scattering of light when it is passed through a colloid or suspension. This is because of the interaction of the light rays by the particles of colloid or suspension which act as obstacles in the path of light. This result in the scattering of beam and thus path of light become visible.

This phenomenon is observed only in colloid or suspension . This is not observed in true solutions since particles of true solution are too small to scatter the light. Thus the solution A must be a colloid or a suspension.