IF the solution is diluted, can the path of light be visible?

Account for the following: When a beam of light is passed through the colloidal solution, the path of light becomes visible.

The path of light is _______

Direct a beam of light from a torch or a laser beam on the test tubes. Is the path of the light beam visible in the liquid?

When a beam of light was passed through the solution of a substance 'A' dissolved in water, the path of light could be seen. Predict the nature of the solution.