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

To solve the question regarding what is observed during the purification of colloidal sol by ultracentrifugation, we can break down the process step-by-step:

### Step 1: Understanding Ultracentrifugation
Ultracentrifugation is a technique used to separate particles in a colloidal solution based on their size and density by applying a high centrifugal force.

**Hint:** Think about how centrifugal force works to separate substances based on their mass.

### Step 2: Setting Up the Experiment
In this process, a colloidal solution is placed in a centrifuge tube. The tube is then spun at a very high speed.

**Hint:** Consider what happens to particles when they are subjected to rapid spinning.

### Step 3: Action of Centrifugal Force
As the centrifuge spins, the centrifugal force acts on the colloidal particles. This force causes the heavier colloidal particles to move outward and settle at the bottom of the tube.

**Hint:** Visualize the motion of particles in a spinning environment and how gravity and centrifugal force interact.

### Step 4: Separation of Colloidal Particles and Impurities
After sufficient spinning, the colloidal particles, which are denser, settle down at the bottom of the centrifuge tube, while the lighter impurities remain suspended in the liquid above.

**Hint:** Think about the differences in density between the colloidal particles and the impurities.

### Step 5: Conclusion
The primary observation during ultracentrifugation is that the colloidal particles settle at the bottom of the centrifuge tube, effectively separating them from the impurities.

**Final Answer:** The colloidal particles are settled at the bottom of the centrifuge tube.

### Summary of Steps:
1. Understand ultracentrifugation.
2. Set up the experiment with a colloidal solution.
3. Apply centrifugal force by spinning the tube.
4. Observe the separation of particles based on density.
5. Conclude that colloidal particles settle at the bottom.