Answer the question on the basis of passage given below:

A colloid is a heterogenous system in which a substance is dispersed (dispersed phase) as fine particles in another substance called dispersion medium. Their particle size is intermediate between that of pure solutions (<1 nm) and suspension (>1000 nm).

They are known for interesting properties such as enormous surface area, Tyndall effect, Brownian Motion etc. They are widely used in industries and day to day life. Some prominent uses of colloids are those in smoke precipitators, purification of water, medicines cleansers etc.

Stability of a colloid is intermediate between that of a solution and suspension. This stability can be attributed to ____.

A. Presence of charge on the particles of dispersed phase.
B. Prolonged mechanical stirring.
C. Solvation by the dispersion medium.
D. Brownian Motion.
E. Dialysis

Choose the correct answer from the options given below:

A, C and D only

The correct answer is Option (3) → A, C and D only.

The stability of a colloid is attributed to several factors, particularly the behavior of the particles in the dispersed phase and how they interact with the dispersion medium. Here's a detailed explanation of the factors:

Factors Contributing to Colloidal Stability:

A. Presence of charge on the particles of the dispersed phase:

Colloidal particles typically acquire an electric charge due to the adsorption of ions. This charge causes electrostatic repulsion between the particles, preventing them from aggregating and settling, thus contributing to colloid stability.

C. Solvation by the dispersion medium:

The particles of the dispersed phase are often surrounded by molecules of the dispersion medium, which helps stabilize the colloid by creating a protective layer around the particles. This prevents them from coming together and settling.

D. Brownian motion :

Colloidal particles exhibit random movement due to collisions with molecules of the dispersion medium. This constant motion prevents the particles from settling under the influence of gravity, contributing to the stability of the colloid.

Other Factors:

B. Prolonged mechanical stirring : While stirring can help disperse particles, it does not contribute to the inherent stability of a colloid. Stability comes from electrostatic and solvation effects.

E. Dialysis: Dialysis is a method used to purify colloids by removing impurities, but it does not directly affect the stability of the colloidal system itself.

Correct Answer:

The factors A, C, and D (charge on particles, solvation, and Brownian motion) are key contributors to the stability of a colloid.

Therefore, the correct answer is: A, C, and D only