Question

The rate of sedimentation of a particle is dependent on the:

• A. density of the particle only
• B. size of the particle only
• C. viscosity of the medium only
• D. size and density of the particle along with the viscosity of the medium

Hint:

Sedimentation = (Size + Density) vs. (Medium Viscosity).

Answer 1

The Correct Option is D

Step 1: Concept
Sedimentation rate describes how fast a particle moves through a fluid under a centrifugal or gravitational force.

Step 2: Meaning
This is mathematically described by Svedberg's equation or Stokes' Law.

Step 3: Analysis
The sedimentation velocity $v$ is proportional to: 1. The mass/size of the particle ($r^2$). 2. The density difference between the particle and the medium ($\rho_p - \rho_m$). 3. It is inversely proportional to the viscosity ($\eta$) of the medium, which provides resistance.

Step 4: Conclusion
All three physical parameters—particle size, particle density, and medium viscosity—interact to determine the final sedimentation rate. Final Answer: (D)