The correct option is (c).
Explanation
Colloidal Solutions represent a state of matter intermediate between true solutions and suspensions. They are mixtures where microscopically dispersed insoluble particles of one substance are suspended throughout another substance.
- Statement 1 is Correct: Colloidal solutions appear to be homogeneous to the naked eye (e.g., milk, fog) because the particles are uniformly distributed. However, they are physically heterogeneous mixtures consisting of two phases: the dispersed phase (solute-like) and the dispersion medium (solvent-like).
- Statement 2 is Incorrect: The particles in a colloidal solution have a diameter range of 1 to 1000 nanometers (nm). While they are larger than the particles in a true solution, they are still too small to be seen with the naked eye. They can typically be observed only with the help of an ultramicroscope.
- Statement 3 is Correct: Colloidal particles are large enough to scatter a beam of visible light passing through them. This scattering renders the path of the light beam visible, a phenomenon known as the Tyndall effect. This property distinguishes colloids from true solutions, where particles are too small to scatter light.
Key Takeaway: Colloids are heterogeneous mixtures with particle sizes (1–1000 nm) intermediate between true solutions and suspensions, uniquely characterized by their ability to scatter visible light (Tyndall effect).