Question

Gold sol is not a:

• A. Macromolecular colloid
• B. Lyophobic colloid
• C. Multimolecular colloid
• D. Negatively charged colloid

Hint:

Gold sol is a negatively charged, lyophobic, multimolecular colloid.

Answer 1

The Correct Option is A

To determine which type of colloid gold sol is not, let's explore the different types of colloids mentioned in the options.

1. Macromolecular Colloid:

   Macromolecular colloids involve macromolecules dispersed in a solvent, forming a stable colloidal solution. These colloids have large-sized molecules acting as a single unit in dispersion, like polymers (e.g., starch, proteins). Gold sol, made up of small particles of gold, does not fit this definition as it does not involve large molecules but rather small particles.

2. Lyophobic Colloid:

   Lyophobic colloids are colloids that do not readily dissolve in the medium and are generally unstable. Gold sol is indeed a lyophobic colloid because it does not have an affinity for the dispersion medium (water) and requires stabilizers for formation.

3. Multimolecular Colloid:

   Multimolecular colloids form through the aggregation of a large number of atoms or small molecules forming a colloid. Gold sol is a classic example of a multimolecular colloid, with gold particles formed by aggregation and stabilized by a suitable agent.

4. Negatively Charged Colloid:

   In a negatively charged colloid, the dispersed particles carry a negative charge. Gold sols are often prepared as negatively charged colloids because the adsorption of negatively charged ions onto gold particles causes them to repel each other, preventing settling and maintaining stability.

Based on the explanations above, it is clear that gold sol is not a macromolecular colloid. Instead, it is characterized as a multimolecular and negatively charged colloid that is lyophobic in nature.