Emulsion: These are liquid-liquid colloidal systems, i.e., the dispersion of finely divided droplets in another liquid. If a mixture of two immiscible or partially miscible liquids is shaken, a coarse dispersion of one liquid in the other is obtained which is called emulsion. Generally, one of the two liquids is water. There are two types of emulsions. (i) Oil dispersed in water (O/W type) and (ii) Water dispersed in oil (W/O type).

In the first system, water acts as dispersion medium. Examples of this type of emulsion are milk and vanishing cream. In milk, liquid fat is dispersed in water. In the second system, oil acts as dispersion medium. Common examples of this type are butter and cream.

Emulsions of oil in water are unstable and sometimes they separate into two layers on standing. For stabilisation of an emulsion, a third component called emulsifying agent is usually added. The emulsifying agent forms an interfacial film between suspended particles and the medium. The principal emulsifying agents for O/W emulsions are proteins, gums, natural and synthetic soaps, etc., and for W/O, heavy metal salts of fatty acids, long chain alcohols, lampblack, etc.

Which of the following statements regarding emulsions is false?

Emulsions cannot be separated into their constituent liquids

The correct answer is option 1. Emulsions cannot be separated into their constituent liquids.

The statement that is false regarding emulsions is: Emulsions cannot be separated into their constituent liquids.

Emulsions can, in fact, be separated into their component liquids through various methods. Here's a breakdown of the statements:

• Emulsions cannot be separated into their constituent liquids: While emulsions are stable mixtures, they are not permanent. Techniques like centrifugation (using high force), creaming (allowing gravity to separate phases), and addition of specific chemicals (demulsifiers) can break the emulsion and separate the oil and water phases.
• Emulsions show Brownian motion: This is true. Brownian motion refers to the erratic movement of microscopic particles suspended in a fluid. In emulsions, the dispersed droplets (oil or water) are large enough to exhibit Brownian motion, which can be observed through a microscope.
• Emulsions show Tyndall effect: This is also true. The Tyndall effect is the scattering of light by particles suspended in a medium. Emulsion particles have a size range that can cause light scattering, making the emulsion appear cloudy or opaque.
• Emulsions exhibit Electrophoresis and Coagulation: This is true. Electrophoresis is the movement of charged particles in an electric field. Some emulsions can have charged droplets that move under an electric field. Coagulation refers to the clumping together of dispersed particles. Certain factors like adding electrolytes or changing pH can destabilize an emulsion and cause coagulation, leading to separation of the phases.

Therefore, while emulsions are stable mixtures, they are not permanent and can be separated using various methods. The other statements highlight some of the physical properties exhibited by emulsions.