Ultra-centrifuges are applied to separate extremely fine _____________ solid particles?
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Answer: C. Colloidal
Explanation
Ultra-centrifuges generate extremely high centrifugal force fields capable of separating extremely fine colloidal solid particles from a liquid phase. Colloidal particles remain stably suspended under normal gravity due to Brownian motion and small mass. Massive centrifugal accelerations exceeding standard gravity by hundreds of thousands of times force colloids to sediment. An ultra-centrifuge operates at extremely high rotational speeds, often reaching tens of thousands of revolutions per minute. The sedimentation rate of colloidal particles is proportional to the centrifugal acceleration and particle size squared. Precision rotors must be balanced carefully to prevent catastrophic mechanical failure at extreme rotational speeds.
Option A is incorrect because coarse particles settle rapidly under normal gravity and do not require ultra-centrifuges. Option B is vague and less precise than specifying colloidal particles which require extreme centrifugal forces. Option D is wrong since dissolved molecules form true solutions and cannot be separated by standard centrifugal forces.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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