Which of the following statements are correct? (1) Electro-osmosis is the movement of the particles of dispersion medium under the influence of an electric field. (2) On the application of an electric field, the particles of a lyophobic sol may move in either direction or not move at all. (3) Surface tension of lyophobic sols is similar to that of the dispersion medium. (a) 1 and 2 (b) 1 and 3 (c) 2 and 3 (d) 1,2 and 3

Lyophobic sols, by definition, are colloidal systems in which the dispersed phase does not have an affinity for the dispersion medium. This lack of attraction results in sols that are generally not very stable and require stabilizers to maintain their dispersed state. In an electric field, the behavior of lyophobic sol particles can be quite unpredictable. Due to their lack of affinity for the medium, these particles may become charged and get influenced by the electric field; however, it is not always clear which direction they will move in. Factors such as the nature of the charged surface, the type of the ions in the dispersion medium, and the pH can all play a role in determining the movement. This behavior is crucial for understanding filtration processes and tailoring industrial applications like wastewater treatment where the removal of colloidal particles is desired.

The irregular movement of lyophobic sols under an electric field can be a challenge when trying to manipulate or separate these sols for various chemical processes, and thus, requires a detailed analysis of their properties and the conditions impacting their behavior.

Surface tension is a property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules. In the context of sols, particularly lyophobic ones, the surface tension becomes an interesting aspect to consider. Lyophobic sols tend to have higher surface tension than that of their dispersion medium. This is because the dispersed particles do not interact well with the medium, which means they do less to reduce the cohesive forces at the surface. As a result, the surface of a lyophobic sol behaves more like that of a pure solvent, exhibiting higher surface tension.

Understanding surface tension is critical when examining phenomena such as capillary action, emulsification, and the stability of colloids. Additionally, in industrial applications, surface tension can affect processes like paint formulation, inkjet printing, and the manufacture of aerosols, where the behavior and stability of sol particles are crucial.

The dispersion medium in a colloidal system or sol is the continuous phase that hosts the dispersed particles. It can be any state of matter, such as a liquid, gas, or solid, but for colloidal solutions, it is most commonly a liquid. The medium's properties, including its viscosity, dielectric constant, and pH, can significantly influence the stability and behavior of the colloidal system. The interactions between the dispersed particles and the dispersion medium determine the overall properties of the sol, such as its optical characteristics, electrical conductivity, and reactivity.

In the specific case of lyophobic sols, the medium often requires additives to improve stability, as without them, the particles would rapidly aggregate and lead to the sol's breakdown. Therefore, studying the nature of the dispersion medium and how it interacts with colloidal particles becomes essential when trying to manipulate or utilize colloidal systems for practical applications like drug delivery systems, paints, or photonic crystals.