The correct option among the following is

Options

A. Colloidal particles in lyophobic sols can be precipitated by electrophoresis
B. Brownian motion in colloidal solution is faster if the viscosity of the solution is very high.
C. Colloidal medicines are more effective because they have small surface area
D. Addition of alum of water makes it unfit for drinking.

Answer

To solve the question regarding the correct option among the statements provided, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement Analysis:**
- **Statement A:** "Colloidal particles of lyophobic sols can be precipitated by electrophoresis."
- **Explanation:** Electrophoresis is the movement of charged particles in a liquid under the influence of an electric field. Lyophobic sols (sols with poor solvent affinity) can indeed be precipitated by applying an electric field, causing the particles to migrate towards the electrodes. This statement is **correct**.

2. **Statement B:** "Brownian motion in colloidal solutions is faster if the viscosity of the solution is very high."
- **Explanation:** Brownian motion refers to the random movement of particles suspended in a fluid. If the viscosity of the solution is high, it creates more resistance to the movement of the particles, thus slowing down Brownian motion. Therefore, this statement is **incorrect**.

3. **Statement C:** "Cholera medicines are more effective because they have smaller surface area."
- **Explanation:** The effectiveness of medicines, including cholera medicines, is generally related to their surface area. A larger surface area allows for more adsorption of the medicine onto the target sites in the body, enhancing its effectiveness. Thus, this statement is **incorrect**.

4. **Statement D:** "The addition of alum to water makes it unfit for drinking."
- **Explanation:** Alum is commonly used in water treatment processes as a coagulating agent. It helps to remove impurities from water, making it cleaner and safer for drinking. Therefore, this statement is **incorrect**.

### Conclusion:
Based on the analysis of the statements:
- **Only Statement A is correct.**

### Final Answer:
The correct option among the following is **Statement A**.

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