Incorrect statement about lyophobic colloids

Options

A. They are readily precipitated by adding small amount of electrolyte
B. They can be prepared by special methods
C. They are irreversible
D. They do not required stabilizing agents for their preservation

Explanation

To identify the incorrect statement about lyophobic colloids, we need to understand their characteristics and properties. Here’s a step-by-step solution:

### Step 1: Define Lyophobic Colloids
Lyophobic colloids are colloidal systems that do not have an affinity for the dispersion medium. This means that the particles of the lyophobic colloid do not interact favorably with the solvent.

**Hint:** Remember that "lyophobic" translates to "fear of solvent," indicating a lack of affinity.

### Step 2: Stability of Lyophobic Colloids
Lyophobic colloids are generally unstable. They can easily coagulate or precipitate when a small amount of electrolyte is added or when subjected to heat. This instability is a key characteristic.

**Hint:** Think about how stability relates to the interaction between colloidal particles and the dispersion medium.

### Step 3: Preparation of Lyophobic Colloids
Lyophobic colloids require special methods for their preparation, such as the dispersion method (breaking down larger particles) and the aggregation method (forming clusters of particles).

**Hint:** Recall the two methods of preparation and how they differ in terms of particle size manipulation.

### Step 4: Irreversibility
Once formed, lyophobic colloids are generally irreversible, meaning that they cannot be easily separated from the dispersion medium.

**Hint:** Consider what "irreversible" means in the context of physical changes and stability.

### Step 5: Need for Stabilizing Agents
A crucial point is that lyophobic colloids require stabilizing agents to maintain their stability. Since they are unstable, these agents help prevent coagulation and maintain the colloidal state.

**Hint:** Think about why an unstable system would need external support to remain in a colloidal form.

### Conclusion
Based on the above points, the incorrect statement about lyophobic colloids is: "They do not require a stabilizing agent for their preservation." This statement is false because lyophobic colloids are indeed unstable and require stabilizing agents to maintain their colloidal state.

**Final Answer:** The incorrect statement is: "They do not require a stabilizing agent for their preservation."