During purification of colloidal sol by ultracentrifugation which of the following is . Observed ?

Options

A. Collodial particles are settled at the bottom of ultracentrifuge tube
B. Impurities are settled at the bottom of the ultracentrifuge tube
C. Impurities are removed through ultrafilters
D. Its rate can be increased by applying pressure

Answer

**Step-by-Step Solution:**

1. **Understanding Ultracentrifugation:**
- Ultracentrifugation is a technique used to separate colloidal particles from impurities based on their size and density. It involves spinning a sample at very high speeds in a centrifuge.

**Hint:** Remember that ultracentrifugation relies on the principle of centrifugal force to separate particles.

2. **Process of Ultracentrifugation:**
- An impure colloidal sol is placed in a tube, which is then rotated at high speeds. This rotation generates a strong centrifugal force.

**Hint:** Consider how the force acts differently on colloidal particles and impurities due to their size and density.

3. **Behavior of Colloidal Particles:**
- During the process, the colloidal particles, which are larger and denser than the surrounding liquid, will settle at the bottom of the centrifuge tube.

**Hint:** Think about what happens to heavier particles in a liquid when subjected to a strong force.

4. **Behavior of Impurities:**
- Soluble impurities, being smaller and less dense, remain suspended in the liquid and do not settle at the bottom.

**Hint:** Reflect on the nature of soluble impurities and how they interact with the liquid medium.

5. **Decantation:**
- After centrifugation, the liquid containing the soluble impurities is carefully decanted off, leaving behind the settled colloidal particles.

**Hint:** Consider the method of separating the liquid from the solid after centrifugation.

6. **Evaluating the Options:**
- Based on the above understanding:
- **Option 1:** Colloidal particles are settled at the bottom of the ultracentrifuge tube. (Correct)
- **Option 2:** Impurities are settled at the bottom of the ultracentrifuge tube. (Incorrect)
- **Option 3:** Impurities are removed through ultrafilters. (Incorrect)
- **Option 4:** Its rates can be increased by applying pressure. (Incorrect)

**Hint:** Analyze each option critically based on the principles of ultracentrifugation.

7. **Conclusion:**
- The correct observation during the purification of colloidal sol by ultracentrifugation is that the colloidal particles are settled at the bottom of the centrifuge tube.

**Final Answer:** Option 1: Colloidal particles are settled at the bottom of the ultracentrifuge tube.

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