A colloid is a heterogeneous system in which one substance is dispersed as very fine particles in another substance. Their range of diameters is between 1-1000 nm. Based on dispersed phase and dispersion medium, colloids may be of different types like sol, gel, emulsion, aerosol, foam etc. Based on nature of interaction between two phases, sols are divided into Lyophillic and Lyophobic sols. Colloidal solutions exhibit various properties like Tyndall effect, Brownian movement and Electrophoresis. Stability of colloids is due to presence of charge. If somehow charge is removed, the particles will coagulate. Coagulation rate by various solutions containing ions, is decided by Hardy-Schulze rule. Everyday we come across many colloids. The meals we eat, clothes we wear, wooden furniture etc. are largely composed of colloids.

The process of movement of dispersion medium under the effect of electric field is known as

Electroosmosis

The correct answer is option 1. Electroosmosis.

Here is a detailed explanation of each term related to movement of dispersion medium under the effect of electric field:

1. Electroosmosis

Electroosmosis is the movement of the dispersion medium (liquid) in a colloidal system under the influence of an electric field. This phenomenon occurs because the dispersion medium has a net charge when an electric field is applied. The charged particles in the dispersion medium attract or repel, creating a flow of the liquid in a specific direction.

For example, in a colloidal system with a charged surface (like a charged membrane or colloidal particles), applying an electric field causes the liquid to move towards or away from the charged surface. This movement is useful in various applications, including electrokinetic separation techniques and soil remediation.

2. Electrophoresi

Electrophoresis is the migration of charged particles (like colloidal particles or ions) through a dispersion medium under the influence of an electric field. The charged particles move towards the electrode of opposite charge.

In electrophoresis, particles move relative to the medium, and the rate of their movement depends on their charge, size, and the viscosity of the medium. This process is commonly used in biochemical applications to separate proteins, nucleic acids, and other macromolecules based on their size and charge.

3. Brownian Movemen

Brownian movement (or Brownian motion) refers to the random, jittery movement of particles suspended in a fluid (liquid or gas) due to their constant collision with fast-moving molecules in the surrounding fluid. This type of motion is not influenced by an electric field and is a fundamental characteristic of colloidal particles, helping to stabilize them by preventing them from settling out of the dispersion medium.

4. Coagulatio

Coagulation is the process where dispersed particles in a colloidal system aggregate or clump together, leading to the formation of larger particles or precipitates. This typically occurs due to the addition of electrolytes or coagulants, which neutralize the charges on the particles and reduce their repulsion, allowing them to stick together and form aggregates.

In summary:

Electroosmosis is the movement of the liquid itself under an electric field.

Electrophoresis is the movement of charged particles within the liquid under an electric field.

Brownian movement is random motion caused by collisions with fluid molecules.

Coagulation involves the aggregation of particles in the dispersion medium.

Each of these phenomena plays a distinct role in the behavior and manipulation of colloidal systems.