Which one of the following method is commonly used method for destruction of colloid:

Options

A. Dialysis
B. Condensation
C. Filteration by animal membrane
D. By adding electrolyte

Answer

To determine the commonly used method for the destruction of colloids, we need to analyze the options provided and identify which one leads to the precipitation or destruction of colloids.

### Step-by-Step Solution:

1. **Understanding Colloids**:
- Colloids are mixtures where tiny particles are dispersed throughout another substance. They have a stable suspension due to the charge on their surface.

2. **Analyzing the Options**:
- **Option 1: Dialysis**
- This method involves the separation of colloids from impurities by using a semi-permeable membrane. It is primarily a purification process and does not lead to the destruction of colloids.

- **Option 2: Condensation**
- This process is used to form colloids by aggregating particles. It does not precipitate or destroy existing colloids, but rather creates them.

- **Option 3: Filtration**
- Filtration is a method used to separate solids from liquids or gases. While it can purify colloids, it does not effectively destroy them.

- **Option 4: Adding Electrolyte**
- When an electrolyte is added to a colloidal solution, it neutralizes the charge on the colloidal particles. Once the charge is neutralized, the particles can aggregate and precipitate out of the solution, effectively destroying the colloid.

3. **Conclusion**:
- Based on the analysis, the method that is commonly used for the destruction of colloids is **Option 4: Adding Electrolyte**.

### Final Answer:
The commonly used method for the destruction of colloids is **by adding electrolyte**.

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